The last digit of $5^{25}$ is .......

Express $5005$ as a product of its prime factors.

$A$ positive integer is of the form $3q + 1$,where $q$ is a natural number. Can you write its square in any form other than $3m + 1$,i.e.,$3m$ or $3m + 2$ for some integer $m$? Justify your answer.

$\sqrt{12}$ and ........ are like surds.

For any positive integer $n,$ prove that $n^{3}-n$ is divisible by $6.$

The number $3 \times 15 \times 11 + 11$ is a . . . . . . number.