The simple interest on a certain sum at the rate of 16.25% for 4 years is Rs. 12600 less than the principal. Find out half of principal.

36000 18000 20000 54000

18000

Total SI for 4 years = 16.25 × 4 = 65% Let principal is = 100%            100 - 65% = 35% given → 35% = 12600               1%  = 360 ⇒ 100 % = 36000 \(\frac{1}{2}\)(P) = 18000