"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?

lets assume grann'y age is 10x+y and thus fathers age is 10y+x

10x+y-45=10y+x
9x-9y=45
x-y=5
thus the digits in grann'y age and fathers age,may individually be prime numbers but must be mulitiples of 9.

now the job becomes easy just find those multiples of 9 which are made up of prime numbers and find their difference.

the numbers being 27 and 72 ;their difference being 45

Posted by akila on 2003-03-03 00:54:18