CAT (QA) PYQs

The sum of digits of the number $(625)^{65} \times (128)^{36}$, is

The sum of all the digits of the number $(10^{50}+10^{25}-123)$, is

For any natural number $n$, let $a_{n}$ be the largest integer not exceeding $\sqrt{n}$. Then the value of $a_{1}+a_{2}+\ldots .+a_{50}$ is