Question

Check whether 21 and 25 are co- prime or not

Answer 1

$$\begin{gathered} \mathrm{The}\mathrm{prime}\mathrm{factorisation}\mathrm{of}21\mathrm{and}25\mathrm{are}: \\ 21=3\times 7 \\ 25=5\times 5 \\ \mathrm{So},\mathrm{HCF}\mathrm{of}21\mathrm{and}25=1 \\ \mathrm{Hence}21\mathrm{and}25\mathrm{are}\mathrm{coprime}\mathrm{numbers}. \end{gathered}$$