Numbers Questions

Find the average of all prime numbers between 20 and 50.

What is the sum of the first 13 terms of an arithmetic progression if the first term is -10 and last term is 26?

The sum of a non-zero number and thrice its reciprocal is 52/7. Find the number.

A number is greater than twice its reciprocal by 31/4. Find the number.

What is the digit in unit's place of the product 51 x 52 x 53 ...... 59?

Sum of twice a fraction and 5 times its reciprocal is 7. What is the fraction?

The 7th and 12th term of an arithmetic progression are -15 and 5 respectively. What is the 16th term?

Product of digits of a 2-digit number is 18. If we add 63 to the number, the new number obtained is a number formed by interchange of the digits. Find the number.