Question

The solution of the following by using suitable identities:
${799}^2$ is -----

Answer 1

The given expression ${799}^2$ can be rewritten as $(800-1{)}^2$ and we solve it as follows:

$(800-1{)}^2=(800{)}^2+(1{)}^2-(2\times 800\times 1)(\because (a-b{)}^2=a^2+b^2-2ab)=640000+1-1600=640001-1600=638401$

Hence, ${799}^2=638401$.