There are some friends, all less than 20 years. When paired amongst themselves they realize that the sum of their ages is a multiple of 5. If their ages are distinct prime numbers, then the number of possible pairs are: 

The difference between the average of squares of the last four numbers and the product of the first two numbers of 6 consecutive odd numbers is 114. Find the first number.

The sum of four numbers is 64. If we add 3 to the first number, 3 is subtracted from the second number, the third is multiplied by 3 and the fourth is divided by 3, then all the results are equal. What is the difference between the largest and the smallest of the original number?

If 999x + 888y = 1332 and 888 x + 999y = 555.then the value of (x + y) is-

The difference between the greatest and the least four-digit numbers that begins with 3 and ends with 5 is: 

What value will come in place of question mark (?) in the questions given below?

(4425÷25) ×(8.5×16) = ?

4⁶¹ + 4⁶² + 4⁶³ + 4⁶⁴ is divisible by: 

What will be come in place of question mark(?) in the following number series?
3, 22, ? , 673, 2696, 8093