Question

Choose a number between 61 and 107 that is a multiple of 4,5, and 10

Answer 1

$4|2 \\ 2|2 \\ 1 \\ 4=2^2\\ \\ 5|5 \\ 1 \\ \\ 10|2 \\ 5 \ |5 \\ 1 \\ \\ 10=2*5 \\ \\ \ [ 4;5;10 \ ]=2^2*5=4*5=20 \\ \\ 61 < M _{20} < 107 \\ \\\boxed{ M_{20}= \{ 80;100 \}}$

Answer 2

$4\times5=20-is\ a\ multiple\ of\ 10\\\\20\times4=\boxed{80}\\\\20\times5=\boxed{100}$