At $20\%$ p.a. compounded annually, a sum first exceeds double its value after how many full years?

Question

Aicharya · Accepted Answer

$(1.2)^{1} = 1.20$, $(1.2)^{2} = 1.44$, $(1.2)^{3} = 1.728$, $(1.2)^{4} = 2.0736$. So the sum first exceeds double after $4$ full years.

Solution