In how many years will money double at 10% SI?

Explanation

• Money doubles when the interest earned equals the original principal, so SI = P.
• Substitute into SI = (P × R × T)/100: P = (P × 10 × T)/100, which leaves T = 10 years.
• The principal cancels out, so the answer does not depend on how much money is invested.
• The simple interest shortcut is T = 100 ÷ R, and 100 ÷ 10 gives 10 years directly.
• To triple the money the interest must equal twice the principal, which takes 200 ÷ R = 20 years.
• Simple interest doubling MCQs are a regular feature of FPSC and NTS papers, and T = 100 ÷ R answers them instantly.