Find the least number of soldiers in a regiment which can allow being drawn up in a hollow square $8$, $10$, $12$ or $15$ deep and also into a solid square.

How many $\frac{1}{8}$'s are there in $37\frac{1}{2}$?

${\left(1.88\right)}^2+{\left(2.12\right)}^2+2\left(1.88\right)\left(2.12\right)=?$

The greatest number of four-digits which is divisible by each one of the numbers $12$, $18$, $21$ and $28$ is: