if difference between compound interest and simple interest on a sum at 10 % p . a . for 2 years is rs . 65 then sum is
"p ( r / 100 ) ^ 2 = c . i - s . i p ( 10 / 100 ) ^ 2 = 65 6500 answer : b"
divide(65, multiply(divide(10, const_100), divide(10, const_100)))