Calculate this~!

MUST be solved in your head!

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155 Replies - 13378 Views - Last Post: 04 May 2009 - 08:17 PM

#107 BigAnt   User is offline

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Re: Calculate this~!

Posted 19 January 2009 - 10:10 AM

0?

I have never had modular arithmetic, but if mod is just taken as remainder it can easily be seen that 2^1001mod33 will be 2 and 2-2=0.

#108 BigAnt   User is offline

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Re: Calculate this~!

Posted 19 January 2009 - 09:33 PM

Well when we wait to verify the solution or not lets try this:

The Puzzle: The following equation is wrong: 101 - 102 = 1

Move one numeral to make it correct.

#109 Gloin   User is offline

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Re: Calculate this~!

Posted 20 January 2009 - 04:50 AM

I'm very impressed.. Great job BigAnt!! 0 was the correct answer.

I doubt this is what you expected as answer but if you take the least significant digit of the first term and move it onto the equality character you get a not equal to sign.

10 - 102 != 1

I just figured the correct answer as well when posting.. Just move the 2 to make it an exponent..

101 - 10^2 = 1

This post has been edited by Gloin: 20 January 2009 - 04:51 AM


#110 BigAnt   User is offline

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Re: Calculate this~!

Posted 20 January 2009 - 07:42 AM

Yes the second one was what I was looking for :D

The Puzzle: Two friends have a nice meal together, and the bill is $25

The friends pay $15 each, which the Waiter gives to the Cashier

The Cashier hands back $5 to the Waiter

The Waiter keeps $3 as a tip and hands back $1 each

So, the friends paid $14 each for the meal, for a total of $28. The Waiter has $3, and that makes $31. Where did the other dollar come from?

This post has been edited by BigAnt: 20 January 2009 - 03:16 PM


#111 BigAnt   User is offline

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Re: Calculate this~!

Posted 23 January 2009 - 09:31 AM

Actually someone already asked this, just with different numbers...

SO lets try this:

If one and a half hens lay one and a half eggs in one and a half days, how many eggs does one hen lay in one day?

#112 Auzzie   User is offline

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Re: Calculate this~!

Posted 23 January 2009 - 09:37 AM

Well i would say 2/3rd's of an egg but its a hlaf away guess

#113 BigAnt   User is offline

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Re: Calculate this~!

Posted 23 January 2009 - 09:47 AM

Good guess!

Hens × Days × (DR) = Eggs

1 ½ × 1 ½ × (DR) = 1 ½

DR= 1 ½ / (1 ½ × 1 ½)

DR= 1/(1 ½) = 2/3

So 1 hen in 1 day will lay two-thirds of an egg

Now its your turn to post the problem :D

#114 Auzzie   User is offline

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Re: Calculate this~!

Posted 23 January 2009 - 08:04 PM

A box contains some buttons. 1/4 of them are black, 1/8 of them are red,

and the rest are white. There are 204 more white buttons than red buttons.

How many buttons are there altogether?

#115 Gloin   User is offline

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Re: Calculate this~!

Posted 23 January 2009 - 08:22 PM

There has to be 408 total because 5/8 are white. 5x/8 - 1x/8 = 204 => x/2 = 204 => x = 408

#116 Gloin   User is offline

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Re: Calculate this~!

Posted 23 January 2009 - 08:30 PM

Attached Image

#117 BigAnt   User is offline

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Re: Calculate this~!

Posted 24 January 2009 - 10:46 AM

The 7 and the E

#118 Gloin   User is offline

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Re: Calculate this~!

Posted 25 January 2009 - 06:07 AM

Yep yep!

#119 BigAnt   User is offline

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Re: Calculate this~!

Posted 25 January 2009 - 10:14 AM

Pythagorean Parallelepiped:

You may be familiar with Pythagorean triangles--triangle solutions of the equation x^2+y^2=z^2--such as 3,4,5: 5, 12, 13: etc. The problem now is to find a 3d example--a rectangular parallelepiped whose edges and diagonal can be expressed as integers--i.e., an integral solution of w^2+x^2+y^2=z^2. This problem should be solved mentally.

#120 BigAnt   User is offline

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Re: Calculate this~!

Posted 27 January 2009 - 07:54 AM

What!? Nobody? How about a hint:

Spoiler


#121 Gloin   User is offline

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Re: Calculate this~!

Posted 27 January 2009 - 09:18 AM

19^2 = 15^2 + 10^2 + 6^2
361 = 225 + 100 + 36

Completely forgot about tis question..

Can someone find another?

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