Who can find an answer different than 7.

[jow104]

Not girls, cats in sacks or buses this time.:rolleyes:


Think of a number..............

Add Ten..................

Double the result.............

Subtract 6................

Divide by 2....................

Take away the first number you thought of.........


Mo hijacking :rolleyes:

[Cliff Rogers]

..... Mo hijacking :rolleyes:
My Mo is still right under my nose. :?

[Brickie]

I started with 7 and got 6?:?

Whos Mo?

[Ivan in Oz]

Think of a number..............
x

Add Ten..................
x + 10

Double the result.............
[x + 10] x 2

Subtract 6................
([x + 10] x 2) - 6

Divide by 2....................
[([x + 10] x 2) - 6]/2

Take away the first number you thought of.........
([([ x + 10 ] x 2) - 6]/2) - X
.
.
.
=([([ x + 10 ] x 2) - 6]/2) - X

=([2x + 20 - 6]/2) - X

=([x + 10] - 3) - x

=x +7 -x

=7

:doh: Waste of time

[Ashore]

same thing if you take out the double and divide by 2 just halve the number you subtract

Think of a number
add 10
Subtract 3
take away origional number
Answer 7 :doh:

[jow104]

Ashore, I can see your logic.

But what about the subtract 6 bit?

(I understand the algerbra bit of Ivan)

[Skew ChiDAMN!!]

I keep coming up with 111. :~

Oh... hang on... my calculator is in binary mode...

[Ashore]

Because you don't double you only subtract half of 6 being 3 :2tsup:

[jow104]

Right Ashore, I am not going to play poker with you.:)

[Wongo]

Think of a number
Subtract the same number
Add 7

Do you get 7? :laughing1:

Love your work Ivan:2tsup:

[switt775]

Simple. Make a mistake. (but only 1. If you make 2 mistakes, they might cancel each other out, and you'll accidently get the correct answer.)

[Wongo]

same thing if you take out the double and divide by 2 just halve the number you subtract

Think of a number
add 10
Subtract 3
take away origional number
Answer 7 :doh:


Think of a number
Subtract the same number
Add 7

Do you get 7? :laughing1:

Love your work Ivan:2tsup:

:bgth:

[Greg Ward]

Count your fingers.

Work at a saw mill for 7 years

Count your fingers.

Answer......

[tea lady]

I got -7 by starting with a negative number less than -10 (as in -11, -12, -13)
Do I win a prize?:)

[Wongo]

How did you do that tea lady?

[switt775]

I got -7 by starting with a negative number less than -10 (as in -11, -12, -13)
Do I win a prize?:)
Sadly, no, you just illustrated my point.

Number: -12
Add 10 -12+10 = -2
Double -2 x 2 = -4
Subtract 6 -4 -6 = -10
Subtract original
number: -10 -(-12) = 7

When you subtract a negative, you need to reverse the sign and add it.

So the answer is still 7.:D:D

[Wood Borer]

It works for complex numbers too. I tried 2 + j3.

[Wongo]

Of course it does. See Ivan's post below. It doesn't matter what x is, it will cancel out in the end.:2tsup:



Think of a number..............
x

Add Ten..................
x + 10

Double the result.............
[x + 10] x 2

Subtract 6................
([x + 10] x 2) - 6

Divide by 2....................
[([x + 10] x 2) - 6]/2

Take away the first number you thought of.........
([([ x + 10 ] x 2) - 6]/2) - X
.
.
.
=([([ x + 10 ] x 2) - 6]/2) - X

=([2x + 20 - 6]/2) - X

=([x + 10] - 3) - x

=x +7 -x

=7

:doh: Waste of time

[Stuart]

Subtract original
number: -10 -(-12) = 7

When you subtract a negative, you need to reverse the sign and add it.

So the answer is still 7.:D:D
I'm not going through all the maths to check each step, but this step stood out like a sore thumb

-10 -(-12) = 2 How did you get 7?


(If you make 2 mistakes, they might cancel each other out, and you'll accidently get the correct answer.) Hmmmmm ;)

[tea lady]

:grumble: Maybe I'll just stick to "Mo hijacking".:hijacked::sueme::coffee:

[Wongo]

Simple. Make a mistake. (but only 1. If you make 2 mistakes, they might cancel each other out, and you'll accidently get the correct answer.)


Stuart, that was the 2nd mistake he was talking about.:D

[Wongo]

Damnit Wongo. Read everything before replying.:U

[Ashore]

Duh what do you want the answer to be
0 subtract 20
1 subtract 18
2 subtract 16
3 subtract 14
4 subtract 12
5 subtract 10
6 subtract 8
7 subtract 6
8 subtract 4
9 subtract 2

:doh:

[switt775]

I'm not going through all the maths to check each step, but this step stood out like a sore thumb

-10 -(-12) = 2 How did you get 7?

Hmmmmm ;)


Hmmmmm indeed..... Yes, again illustrating the point well. Two mistakes giving the right answer. I seem to have left out a step (divide by 2), but compensated by not knowing how to subtract two numbers, thus maintaining harmony in the universe...

Here is the original set of instructions, with my (now correct) calculations:

Think of a number.............. -12

Add Ten.................. -12 + 10 = -2

Double the result............. -2 x 2 = -4

Subtract 6................ -4 -6 = -10

Divide by 2.................... -10 / 2 = -5 :doh:

Take away the first number you thought of......... -5 -(-12) = 7 :2tsup:



As Ivan so clearly pointed out, it's impossible to find a number which will give a correct answer other than 7.
Good to see someone is keeping me honest....

[Wongo]

Mo worries switt775. :D

[jow104]

Wish now I hadnt taken the library book back, lots more mathmatical puzzles.

No woodwork in Oz being done, too hot.

No woodwork in UK being done, too cold

It could have kept us busy for the next few weeks.

[Skew ChiDAMN!!]

As Ivan so clearly pointed out, it's impossible to find a number which will give a correct answer other than 7.

Try it with ∞


:innocent:

[Ashore]

or -10 :D

[switt775]

Try it with ∞


:innocent:

Nice try. But according to Wikipedia (which is published on the Internet, so has to be true) infinity is a concept, not a number.

So it doesn't count.

[Blocklayer]

I'm stuck at the add 10 part

[Skew ChiDAMN!!]

or -10 :D

:brava Well caught!

[echnidna]

or -10 :D

:2tsup::2tsup:

[jow104]

Minus 10

How do you do this physically to proove.

i.e. how can you lay down minus ten pieces and then carry on the clculation?

[echnidna]

do the calculation with any other minus number and the end result will be 7.

[jow104]

do the calculation with any other minus number and the end result will be 7.


Bob I mean to have physcially have minus ten pieces or any other minus number of pieces, and then to display it not in an oral or verbal manner.

[Skew ChiDAMN!!]

Don't you have the concept of bills in England?

I think 'tis time for me to emigrate... :U

[echnidna]

you write out 10 iou's.

[jow104]

ious are not allowed at this establishment.

[Ivan in Oz]

and then to display it not in an oral or verbal manner.

Can I relate it to you this way:?

Measure a length of Timber.
Starting half way along, let this be your Reference point;
otherwise known as Zero (Point).

What ever is one side is +ve,
on the other side is -ve.

How far from it is the size of the number, depending what unites you measure in.

Move the reference point [ZERO]

and you change the size of the number which are +ve,
Ditto -ve


Far from the ideal way to explain:no::no::doh:

[jow104]

Ivan,that is a bit like ious.

And I cant seem to grip it in my hand:) (the minus bits)

[Blocklayer]

A little calculator to help you try different numbers

http://www.blocklayer.com/jow104-7.htm


.

[Ivan in Oz]

Ivan,that is a bit like ious.

And I cant seem to grip it in my hand:) (the minus bits)

Well!!
What have you got in your Hand:oo::no::doh:

And what have you got in you head?.........:wink::rolleyes:

Sorry...couldn't resist,
though shouldn't have.

I find maths Interesting and somewhat easyISH:2tsup:

[jow104]

Blocklayer, that was a good post and link.
Tell us please how you made that calculator.

Ivan, I was thinking along the lines of the Dimbleby science lectures that the British BBC does at Xmas time, they do practical/physical illustrations.

[Ivan in Oz]

Thank you BlockLayer,
You saved my Hide.

Nice find:2tsup:

Ta.
Ivan

[Blocklayer]

Blocklayer, that was a good post and link.
Tell us please how you made that calculator.


I just typed it up in notepad when I saw your post.
Its not that difficult.
Just view the source of the page and it should be pretty evident how it works

[Wongo]

What's so special with -10?:?

[ss_11000]

What's so special with -10?:?

its ten less than zero:?

[tea lady]

I use to be good at maths. Now my brain hurts.:doh:

[Wood Borer]

I am all confused but I have just returned home from the pub. -10 still gives a result of 7.

[Groggy]

Think of a number.............. -10

Add Ten.................. -10 + 10 = 0

Double the result............. 0 x 0 = 0

Subtract 6................ 0 -6 = -6

Divide by 2.................... -6 / 2 = -3

Take away the first number you thought of......... -3 -(-10) = 7


Why is minus 10 special, the answer is still 7 :?

[Groggy]

Mind you, try it with pi :D

[Skew ChiDAMN!!]

What's so special with -10?:?


Simple. Make a mistake. (but only 1. If you make 2 mistakes, they might cancel each other out, and you'll accidently get the correct answer.)

:doh:

[Ashore]

pi , well done, no doubling a never ending decimial , though the -10 got a few :D:D

[Ashore]

i.e. how can you lay down minus ten pieces and then carry on the clculation?
Think of a thermometer with plus degrees and minus degrees, or a uni some degrees are a plus and some arn't :doh:

[Skew ChiDAMN!!]

pi , well done, no doubling a never ending decimial

Oh? 2 x 1/3 = 2/3 or, in decimal, 2 x 0.333... = 0.666... no problems there apart from writing them out in full.

Come to that, every real number can be expressed as a "never-ending" decimal. eg. 1 is more accurately expressed as 1.000... and you have no problems doubling that, do you? :U



though the -10 got a few :D:D

:p

[jow104]

Think of a thermometer with plus degrees and minus degrees, or a uni some degrees are a plus and some arn't :doh:


Unsatisfactory solution. I want to see it in the real.:)

[Wood Borer]

John,

Perhaps if you consider the planet earth (proper way up). Imagine the Equator is zero and everything North of it as negative, everything South as positive.

Are you real only when you are in Australia?:U

[Ashore]

Unsatisfactory solution. I want to see it in the real.:)
Well if 10 people go to Uni in england and get an Engineering Degree thats a plus , but if 10 go and get an Arts Degree with a major in flower pressing, then thats a minus (as well as to thier parents bank account and a loss of 4-5 years of their life,) yeah well if your a bloke you could proberly still play for england but its still a minus:D:D:D

[jow104]

Love Australia, only the UK beats it.:)

[Wood Borer]

Yeah but what about all the Poms over there?:wink:

[Cliff Rogers]

Ooooooooooo........ :D

[tea lady]

Ooooooooooo........ :D

Hey! A different answer than 7.:2tsup:

[Wongo]

Why wouldn't Pi work?

Of course it works.

Pi / 2 is a endless decimal.

BUT

(Pi / 2) * 2 = Pi and that is algebra.

Ivan’s post shows it doesn't matter what x (including pi) is , you will get

x + 7 – x = 7

This question works for real numbers, imaginary numbers, rational numbers, irrational numbers, whole numbers or decimals.

:sleep1: Let us know when you've finished Wongo. :D

[Greg Ward]

A certain number consisting of sevens is divisible by 199.

Find the last 4 figures of the quotient without finding the whole quotient.....

In case you've got nothing better to do

Greg

[Wongo]

6823

Well I do have something else to do but these matters need to be dealt with first. :D

[jow104]

Wongo.would you please do that computation using chinese graphics in algerbra and display, so we know that your calculations have been properly construed.

[Wongo]

Let the last 4 digits be ABCD

So 7777…..77777 = …..ABCD * 199

Let just focus on the ABCD * 199 bit

ABCD * 199 =

A*100000 + B*10000 + C*1000 + D*100 + 0 + 0
+
9*A*10000 + 9*B*1000 + 9*C*100 + 9*D*10 + 0
+
9*A*1000 + 9*B*100 + 9*C*10 + 9*D
Now working from the last digit

D = 3 because 9 * 3 = 27 (carry 2 to the next digit)
C = 2 because 2 + 9 * 3 + 9 * 2 = 47 (carry 4 to the next digit)
B = 8 because 4 + 3 + 9 * 2 + 9 * 8 = 97 (carry 9 to the next digit)
A = 6 because 9 + 2 + 9 * 8 + 9 * 6 = 137 Bingo

Sorry this is the best I could do using a keyboard explain a maths problem.

Try 6823 * 199 and see what happens.

[jow104]

That should help you have a good nights sleep.:)

[Ashore]

A certain number consisting of sevens is divisible by 199. do you mean only the number 7 several times or series of the first 7 numbers or numbers that add up to seven indivudally, and any number is devisible by 199 eg 7 divided by 199 = 0.0351758 so are we talking whole numbers only like 4623 :?

Rgds

[Greg Ward]

The number is a series of '7's, no decimals (although that may not affect the outcome in any event...... iI'm not sure)

Now Wongo has the answer for the last 4 digits..... how may '7's in the number itself? (I don't know the answer here and excel won't go past 777777777777777)

Greg

[Wongo]

Greg, unless you give me a piece of Maple for free, I wont continue this question. :D

[Greg Ward]

Wongo,
Doesn't the free maple you got yesterday count?

Tell you what. You want a challenge???

Whoever solves the (non-mathematical) answer to my quiz question regarding the use of the all 26 letters of the alphabet to make up 13 x 7 letter words from the 13 x 5 letter words listed deserves timber to the value of $100 (and that about covers your deador......)

Is that OK with you????
Regards

Greg

[Wongo]

Now Wongo has the answer for the last 4 digits..... how may '7's in the number itself? (I don't know the answer here and excel won't go past 777777777777777)

Greg

Greg, it will be extremely difficult to find out the answer. It will be a very long number. However, I think by using the Remainder Theorem very cleverly, the answer can be found. Still it will take a while.

So the answer exists but it is hard to work out.:doh:

[Greg Ward]

Yeah, I know, I though you may have a Cray or perhaps a crayfish that may be able to give the answer...

Let's not worry about it. It was a good question and well answered.... it fitted into the 'sevens' area well.

Regards
Greg

[Wongo]

Actually I do have the answer and it is

77777777777777777777777777777777777777777777777777777777777777

Now prove me wrong. :D


Wongo (100% in Higher Mathematics 1991 :U)



And the bit of free timber you gave me yesterday wasn't Maple. :D

[Greg Ward]

You need to work on the alphabet word challenge under 'vowel' in the Quiz section to get your freebies.

Maths is obviously too easy for you, we need to get you off the straight and narrow.

7x62 times is really only small number (in relation to many primes and is obviously not a prime in any event.....just give me a little time to divide by 199.... I know the last four digits, but the rest by long hand division will take an hour or so.

Greg

[Wongo]

OK I've got it.

it is 99 sevens.:2tsup:

I am dead serious.:;

[Wongo]

The next one is 198 sevens

Then 297 sevens

Then 396 sevens

Then 495 sevens

God is great. :D

[Greg Ward]

Nobody can check you in any event....

You are right, this does deserve some free maple, do you want the Canadian or US syrup?

Greg

[Wongo]

It will try to explan when I have time. Anyone interested?:D

[Wongo]

Nobody can check you in any event....

You are right, this does deserve some free maple, do you want the Canadian or US syrup?

Greg

Can I have a bit of blackwood instead?

[Greg Ward]

You just got out your book of 'prime numbers' and multiplied them individually x 199 until you got a number that consisted of a series of sevens.

Greg

[ss_11000]

explain away wongo.

[Wongo]

Let the number be 77777….77777
Now rewrite the number to
7 +
70 +
700 +
7 * 10^3 +
7 * 10^4 +
.
.
.
7 * 10^n


knowing
7 / 199 , remainder = 7
70 / 199, remainder = 70
700 / 199, remainder = 103
7000 / 199, remainder = 103 * 10 = 1030 and 1030 / 199, remainder = 35
7 * 10^4 / 199, remainder = 35 * 10 = 350 and 350 / 199, remainder = 151
.
.
.
and so on.

If 77777….77777 is divisible by 199 then the sum of the remainders must be divisible by 199 too.

hence remainder of (7 + 70 + 103 + 35 + 151 + ...) / 199 is 0

In Excel, the table shows remainder of each digit and the sums. The first sum that has 0 as remainder is the answer. See row 100.

[Greg Ward]

I'm impressed!!!!!!!

Definately worth some blackwood.

Wait until I buy the paint.

Greg

[ss_11000]

all i can say is: your a genius. :clap2:

btw - whats a reminder? ( mathematically speaking)

[Wongo]

Sorry dude, I have been missing the "a" all day. I was too excited. It should be remainder.:p

[ss_11000]

Sorry dude, I have been missing the "a" all day. I was too excited. It should be remainder.:p
no worries - so its not some super secret conspiracy of the great mathematicians:rolleyes::D

[tea lady]

You guys! I go away for the day and look what happens behind my back!!
You're all playing with sevens without me!:C
Although I don't think I could have played with them as good as Wongo.:rolleyes:

[Wongo]

Tea lady, mathematics is a form of art.:D

[tea lady]

Maybe you should change you signature to "smarty pants".