"I've always been 45 years older than your Dad", said Grandma to young grandson.

"But now the two digits in my age, both prime, are the reverse of the two in your Dad's age".

How old is Grandma?

If Grandma is 45 years older then the two digits of their ages must have a difference of 5.
The only single digit prime numbers with a difference of five are 2 and 7. 27 + 45 = 72, so Grandma is 72 and the dad is 27.

Posted by Lewis on 2003-06-03 09:03:34