According to Euclid's division lemma,for $a$ and $5$,if $a = 5q + r$ is unique,then $r = \ldots$ is not possible.

Express $156$ as a product of its prime factors.

Every composite number greater than $1$ can be expressed (factorized) as a product of primes,and this factorization is .........,apart from the order in which the prime factors occur.

Write down the decimal expansion of the rational number $\frac{23}{2^{3} 5^{2}}$.

The last digit of $5^n$ is . . . . . . ,where $n \in N$.

Find the square root of $24+2 \sqrt{119}$.