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

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

Which of the following rational numbers has a non-terminating repeating decimal expansion? $(A)$ $\frac{17}{32}$,$(B)$ $\frac{17}{248}$,$(C)$ $\frac{17}{160}$

Prove that if $x$ and $y$ are both odd positive integers,then $x^{2}+y^{2}$ is even but not divisible by $4$.

The pair .......... is a like surds.

Express $404$ as a product of primes.