Question

Find the cube of 2.1 .

Answer 1

We have: 

\[2 . 1 = \frac{21}{10}\]

Also,

\[\left( \frac{m}{n} \right)^3 = \frac{m^3}{n^3}\]

∴ \[\left( \frac{21}{10} \right)^3 = \frac{{21}^3}{{10}^3} = \frac{21 \times 21 \times 21}{10 \times 10 \times 10} = \frac{9261}{1000} = 9 . 261\]