Express $156$ as a product of primes.

If $n$ is an odd integer,then $n^{2}-1$ is divisible by...........

When $(6k+1)^2$ is divided by $6$,the remainder is . . . . . . .

When $(5k+1)^2$ is divided by $5$,the remainder is .......

State whether the following rational number has a terminating decimal expansion or not. If it has a terminating decimal expansion,find it: $\frac{77}{210}$

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