QA Free Quiz || Classification of Numbers

The sum of five consecutive two-digit odd numbers when divided by 3 becomes a perfect square, what is the middle number?

A child was asked to find the sum of the first 100 numbers. While calculating the sum, the child accidentally reversed the digits of two two-digit numbers such that both the reversed numbers were smaller than the original numbers. If the calculated sum is 4996 and all the four numbers (2, whose digits were reversed and 2 reversed numbers) are prime numbers, which of the following can be one of the two original numbers?

Given 4^x – 5^y × 7^z = 1, where x, y, and z are even numbers, then for how many possible values of x will the given equation be true?

If a, (a + 3b), (a + 3b + 2), and (a + 3b + 6) are prime numbers below 100, where a and b are natural numbers, find the number of possible values of a.

In how many ways can 4620 be written as a product of two co-prime numbers?

Find the number of numbers which are co-prime to 900 and less than 900 .