While adding the first few continuous natural numbers, a candidate missed one of the numbers and wrote the answer as 177. What was the number missed?

Which one of the following cannot be the square of a natural number?

The sum of first 45 natural numbers is:

Let m and n be natural numbers. What is the minimum value of (m + n) such that 33m + 22n is divisible by 121?

What are the two natural numbers whose product is 2400 and the sum of whose squares is 5200?

The first pair of numbers bear a certain relationship. The same relationship is required to be found in the other pair, Find that missing number : 35 : 6 : : 120 :?