Cool Math Tricks

Zumikaku · **Posted:** Tue Nov 24, 2009 9:16 pm

This math "wizard" guy just visited our school today. He taught us all kinds of tricks like the magic square, how to figure out what day of a week a date was, and How to figure out the last 3 numbers on someone's drivers license. I'm going to do the magic square trick for you. Give me any number between 100 and 300 that ends in 0 or 5, and I'll fill a 5X5 square with numbers so that every row, column, and diagonal adds up to the number you chose. Who wants to give me a number first?

LightningMan117 · **Posted:** Tue Nov 24, 2009 9:36 pm

Zumikaku · **Posted:** Tue Nov 24, 2009 9:53 pm

Code:

57 34 41 48
38 40 47 49
39 46 53 55
45 52 54 36
51 58 35 42

stevenjackson39 · **Posted:** Tue Nov 24, 2009 9:58 pm

I have a puzzle i'd like to share, if you don't mind

7 7 7 = 100

add two signs (+, -, ., etc.) to make this statement true.

Zumikaku · **Posted:** Tue Nov 24, 2009 10:02 pm

Closest I can get is (7+7) * 7 = 98

cooldude1045 · **Posted:** Tue Nov 24, 2009 10:26 pm

Are you sure there aren't 4 sevens?

ChiCubsFan4 · **Posted:** Tue Nov 24, 2009 10:31 pm

Zumikaku wrote:

Code:

57 34 41 48
38 40 47 49
39 46 53 55
45 52 54 36
51 58 35 42

Those columns add up to 230, not 170.

Zumikaku · **Posted:** Tue Nov 24, 2009 10:39 pm

Oh, crud. I skipped a step. Here we go:

Code:

45 22 29 36
26 28 35 37
27 34 41 43
33 40 42 24
39 46 23 30

PowerPro Jr · **Posted:** Tue Nov 24, 2009 11:06 pm

Zumikaku · **Posted:** Tue Nov 24, 2009 11:21 pm

It has to end in 5 or 0.

Longball714 · **Posted:** Wed Nov 25, 2009 12:42 am

stevenjackson39 wrote:

I have a puzzle i'd like to share, if you don't mind

7 7 7 = 100

add two signs (+, -, ., etc.) to make this statement true.

I remember that one

and cooldude is right, it's supposed to be 7 7 7 7 = 100.

ChiCubsFan4 · **Posted:** Wed Nov 25, 2009 12:50 am

I give up on that one, someone tell me. (In a PM so it doesn't ruin it for anyone else)

Zumikaku · **Posted:** Wed Nov 25, 2009 10:16 am

Longball714 wrote:

stevenjackson39 wrote:

I have a puzzle i'd like to share, if you don't mind

7 7 7 = 100

add two signs (+, -, ., etc.) to make this statement true.

I remember that one

and cooldude is right, it's supposed to be 7 7 7 7 = 100.

Do we get 3 signs then? hmm...
I can still only get to 98

Longball714 · **Posted:** Wed Nov 25, 2009 2:26 pm

Nope, you only have two signs

parentheses, decimals, radicals, exponents, absolute value, etc., also count as signs

Zumikaku · **Posted:** Wed Nov 25, 2009 3:23 pm

OK, does a pair of parentheses count as 1 or 2? And do the ones you don't use combine to 77? (like this: 7 + 77 + 7).

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