The difference between the compound interest and simple interest on a principal amount for 2 years at 10% per annum is Rs 5431. Find the principal amount.

The principal is Rs 543100.

For 2 years the CI - SI difference = P x (r/100)^2.

Here (r/100)^2 = (10/100)^2 = 1/100.

So P x 1/100 = 5431.

P = 5431 x 100 = 543100.