Question

evaluate the following number one shot cut method (39)²

Answer 1

$\boxed{\huge\textbold{\textit{1521}}}$

${To\:find \: - \: {(39)}^{2} = (40 - 1)}^{2} \\\\ Using \: the \: identity, \\ ( {a - b})^{2} = {a}^{2} + {b}^{2} - 2ab \\ \\ = > {40}^{2} + {1}^{2} - (2 \times 40 \times 1) \\ = > 1600 + 1 - 80 \\ = > 1600 - 79 \\ = > 1521$