Find the amount and the compound interest on Rs 160000 for 2 years at 10% per annum, compounded half-yearly.
Principal, $P=$ Rs. 160000
Annual rate of interest, $R=10 \%$
Rate of interest for a half year $=\frac{10}{2} \%=5 \%$
Time, $n=2$ years $=4$ half years
Then the amount with the compound interest is given by
$A=P \times\left(1+\frac{R}{100}\right)^{n}$
$=160000 \times\left(1+\frac{5}{100}\right)^{4}$
$=160000 \times\left(\frac{100+5}{100}\right)^{4}$
$=160000 \times\left(\frac{105}{100}\right)^{4}$
$=160000 \times\left(\frac{21}{20}\right) \times\left(\frac{21}{20}\right) \times\left(\frac{21}{20}\right) \times\left(\frac{21}{20}\right)$
$=(21 \times 21 \times 21 \times 21)$
$=$ Rs 194481
Therefore, compound interest $=$ amount $-$ principal $=\mathrm{Rs}(194481-160000)=\mathrm{Rs} 34481$