Explanation
A prime number is a number that is evenly divisible by only itself and 1. So 61 is the only prime number. (39 is also divisible by 3, 60 is also divisible by 2, and 145 is also divisible by 5.)
\(\sqrt {{{(6 + x)}^2}} = \)
\( (x - 5)({x^2} + 7x + 2) = ? \)
\(2(5+3 \times \sqrt{25}) \div(14-9) \times 4=?\)
\( {({6^3})^9}? \)