Masters Of Age Theory

Two aged Number theory specialists sat at a pub reminiscing about their youth.

Ash said, "Well, it just occurred to me that when we first met, the square of your age contained the same three digits as the square of my age, just in a different order."

Bill said, "If you take the square of the sum of our ages when we met and split it into two 2-digit numbers, you'd have my age then and your age now!"

If B is Bills age when they first met and A is Ash's age now, your answer should be in the format B.A with a decimal point between the two ages.

Split it into 2 two-digit numbers means for example if the number is 1234. 12 will be one age and 34 the other.

Image credit: Wikipedia


The answer is 16.81.

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7 solutions

Satyen Nabar
Feb 25, 2014

When Ash and Bill first met, their squares had only three digits, so the oldest they could have been was 31. That means that there were only a few possible ages the two of them could have been. Those being : 14 & 31 (196 & 961), 13 & 31 (169 & 961), 16 & 25 (256 & 625), 12 & 21 (144 & 441), 13 & 14 (169 & 196).

Now the square of the sum of each of these pair of ages are respectively: 2025, 1936, 1681, 1089, 729.

Bill was 16 when they first met and Ash is 81 now.

The problem wording is vague. It says the square of the sum of their age when split into two 2-digit numbers gives Bill's age then and Ash's age now. It is not clear that the 4 digit number is to be split down the middle. The answer of the sum of the square could have been 1936 and be split into 13 and 96 or 13 and 69.

Tong Choo - 7 years, 3 months ago

took me a long time to do it

Priyank Kumar - 7 years, 3 months ago

the question is quite unclear and ambiguous, tsk!

Hans Lawrence Dela Cruz - 7 years, 3 months ago

i solved with same logic .

Abyn Scaria - 7 years, 3 months ago

I also solved in the same way.

KAUSTUBH PANDEY - 7 years, 3 months ago

i did it the same way..

Vaibhav Agarwal - 7 years, 3 months ago

Great! I did this using the same logical approach. :)

Leo Draper - 7 years, 3 months ago

The question could have been presented in far better way. Why couldn't they be 2 years old and 20 years old?

Dhruv Toshniwal - 7 years, 2 months ago

doesn't make any sense!! So bill doesn't grow up then? he still 16 while Ash turning 25 into 81.. or i just wrong in reading this problem?

great tough problem btw

Naufal Purnama Hadi - 7 years, 2 months ago

Log in to reply

edit.. i'm so wrong about this i'm sorry... it's a bit ambigous in "you'd have my age then and your age now!" i thought 'my age' is Bill's age now

Naufal Purnama Hadi - 7 years, 2 months ago
Vivek Pathak
Mar 29, 2014

Least and largest numbers with a square of 3 digits=11 and 31 respectively. Numbers between 11 and 31 (inclusive) having similar digits in their square :( 13,14,31) ,(16,25),(12,21) . Taking squares of : 13+14=729 14+31=2025 13+31=1936 16+25=1681 12+21=1089 Only 1681 satisfies the given criteria.

Shuvayan Das
Mar 15, 2014

There are only two numbers i.e 25 & 16 whose squares have the same digits 625 and 256. So summing them and squaring gives us 41^2 = 1681. So 16.81 is the answer.

25 and 16 isn't d only pair.Take a look over these....12 and 21, 31 and 13 , 13 and 14, 14 and 31.

shivam sharma - 7 years, 2 months ago
Amiya Mishra
Apr 2, 2014

25^2=625;16^2=256; 6,2&5 are in different order in two squared numbers.16+25=41;41^2=1681;16 is one of the ages of them when they first met.so the ans is 16.81.

Vivek Singh
Mar 10, 2014

When bill and ash meet, their ages square has only three digit, and which are common in sq. of both. First two no. represent bill's age when they first met and other two digit represent ash's present age, so their should be a comparable difference b/w the two. So, their are only two possible outcomes i.e 16 & 25{256 & 625} or 12 & 21{144 &441}. square's = 1681 & 1089 respectively. Hence, Bill was 16 when they first met and now.Ash is 81

Lalu Zam
Mar 6, 2014

16^2=256 and 25^2=625. Then the square sum of both age is: 41^2=1681 where the first 2 digits is the age of B when they first met. The last 2 digits is A 's age now

Payal Agarwal
Mar 3, 2014

Bills age when they first met is 16 and Ash age is 25. (16)^2=256 & (25)^2=625 which have same digits arranged differently. 16+25=31. (41)^2=1681. 16 is age of bills then and 81 age of ash now.

problem wording is very wrong

sanyam khankhoje - 7 years, 3 months ago

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