ok so has anyone got a really gud maths tricks like......?

Question

pick a no. between 1-10, double it, add thirty, take away the original no. and half it and uend up with15

Answer 1

Actually, U did it wrong.
Pick any number.
Double it.
Add, let's say, 30.
Divide by two.
Subtract your original number from the number you have now.
Your answer is 15.
The answer is always half of the number the asker says to add in step four.
I use this to make people think I'm psychic.

nwordjim is cheating.



Chris C. ~ Because you left out a step. Try it again.
Wee Stoater ~ You left out a step. Try it again.

M

Answer 2

Multiply two or more numbers, with one divisible by 9. Add up the digits till you get a single digit and it will be 9.
999*999=998001
9+9+8+0+0+1=27
2+7=9

999*999*13=12974013
1+2+9+7+4+0+1+3=27
2+7=9

4*9=36
3+6=9

Answer 3

Problem with nwordjim's math's trick. I have a yellow and brown spotted jaguar from Djoubiti and I also have a white oryx from Dominica. There are other countries apart from Denmark that start with the letter D.

My maths trick:

Write down any three digit number(say 694)
Write it down backwards and subtract the smaller number from the larger.

694 - 496 = 198

Now write down your answer backwards and add them together (the answer will always be 1098).

198 + 891 = 1098.

Now go, amaze your friends.

Harry: Your trick works because 7 x 11 x13 = 1001. You multiply that any 3 digit number and you will always get the three digit number repeated.

Answer 4

heres two tricks

1) ask someone to name the highest real number that is less than. most people will say 0.99999.....(recurring) but they are wrong as 0.99999...(recurring) isnt less than 1, its actually equal to 1.

given that :-

0.9999999....(recurring) = 0.9 + 0.09 + 0.009 + 0.0009 + ..........

we can use the geometric progression with :-

a = 0.9
r = 0.1
n -> infinity

now the sum of the first n terms is :-

a(1 - r^n)/(1 - r) = 0.9(1 - 0.9^n)/(1-0.1) = 1 - 0.9^n

now as n -> infinity, 0.9^n -> 0 and therefore 1 - 0.9^n -> 1

therefore :-

0.999999.....(recuring) = 1

and so there is no largest real number less than 1 unless you say 0.9999......999998 with an infinate number of 9's in the middle but most people dont really count that as a number.


2) use a mathematical proof to prove to the world that women are evil (this was great among the maths students at uni). firstly, e all know that women require Time and Money and so we use the equation :-

Women = Time x Money

but we've all heard of the phrase that "Time is Money" and so we make this substitution to get :-

Women = Time x Money = Money x Money = Money^2

but we are also always told that "Money is the root of all evil", so making this substitution gives:-

Women = Money^2 = [sqrt(Evil)]^2 = Evil

Therefore:-

Women = Evil

No more proof needed. we all knew it but now we have the evidence to back it up!!!

THANK YOU.........(applause)

Answer 5

Spirit of radio - I chose the no 5 before reading any of the other answers and I was going to say it didn't work but already seen it's been done!
5 times 2 = 10
10 + 30 = 40
40 - 5 = 35
35/2 does not = 15!!

How do you get it to turn out to 15 then???

Answer 6

Try this as you read it, the answer is at the bottom.

pick a number between one and ten
multiply by 9
take the sum of the digits (eg for 86 you do 8+6=14, or for 4 you do 0+4=4)
take away 5.
if a=1, b=2, c=3 etc. find the letter that corresponds to your number.
name a country whose name begins with that letter. (eg if you had six, you'll get F, so the country could be France)
take the second letter of the name of that country, and name an animal whose name starts with that letter (eg for France, 2nd letter is r, so the animal could be rat).
Then think of a colour that animal could be.

I predict that you'll have....








.... Grey Elephants in Denmark


I'm not cheating! How could i be cheating?

Answer 7

Can you give me a six digit number that is perfectly divisible by 7, 11 AND 13.

Answer : Take any three digit number (say, 148) and write it besides itself. The resulting six digit number (148148) is perfectly divisible by 7,11 and 13.

Check it out.

Figure out the "why" by yourselves :)

Answer 8

What is the square root of -1 usually works

Answer 9

Chris C, you've done the steps wrong, mi owd china!
Do it again carefully, it's bound to work with any real numbers, even negatives etc.

Answer 10

I choose 5
double 5 = 10
add 30 = 40
Subtract original number = 35
Halve it = 17.5 .... why isn't it 15 as you say?