Tag Archives: brain teaser

November 2015 Brain Teaser Solution

Which is greater, 2^1100 or 3^700?
Bonus: Approximately how many times greater is it (to the nearest 10)?
Both of these are too large to do on a calculator and will force the calculator into overflow.  So we have to come up  with another way to compare them rather than getting both actual values.
We can write them as:
(2^11)^100   and (3^7)^100 and just compare the
2^11   vs 3^7
2048 vs 2187
so 3^700 is the winner!!
Here is a link to the answer to the bonus
Thanks for solving

June 2015 Brain Teaser Solution

Q: Can you take the clock face below, and cut it into four pieces such that the numerals on each part add up to the same number?

A: The key is to turn the number XI upside down to a IX or:
turn the IX upside down to a XI
The numbers 1-12 add up to 78 which is not divisible by 4
Replace 11 with a 9 and the numbers now add up to 76 which is divisible by 4
and/or replace the 9 with an 11 and now the numbers add up to 80 which is also divisible by 4

May 2015 Brain Teaser Solution

Q: Here is the Math/logic brain teaser that took the Internet by storm in mid-April 2015:

Albert and Bernard just became friends with Cheryl, and they want to know when her birthday is. Cheryl gives them a list of 10 possible dates: May 15 May 16 May 19 June 17 June 18 July 14 July 16 August 14 August 15 August 17

Cheryl then tells Albert and Bernard separately the month and the day of her birthday respectively. Albert: I don’t know when Cheryl’s birthday is, but I know that Bernard does not know too.

Bernard: At first I don’t know when Cheryl’s birthday is, but I know now.

Albert: Then I also know when Cheryl’s birthday is.

So when is Cheryl’s birthday?

A: July 16th.
Can’t be a unique day. Therefore it cannot be May or June.

July 14 July 16
August 14 August 15 August 17

Has to be unique

July 16
August 15 August 17

If Bernard know and Albert now knows that it has to be July 16th. If it was August then Albert would not know.

(Thanks to Adam Schwartz for this solution!)