Find the difference between the compound interest and simple interest on a sum of $₹16,000$for $3$ years if the rate of interest is $2\%$per annum.

Sanjay borrowed $₹12,800$ at the rate of $6 \frac{1}{4}\%$per annum at simple interest. On the same day. he lent it to Rajesh at the same rate but compounded annually. What does Sanjay gain at the end of $2$ years?

In how many years will $₹4,000$ amount to$₹5,324$ at the rate of $10\%$ per annum compounded annually?

At what rate of compound interest will $₹1,250$ amount to $₹1,800$ in $2$years?