0.8% of a number is 31, then find the number.

4⁶¹ + 4⁶² + 4⁶³ + 4⁶⁴ is divisible by: 

Direction : What value should come in the place of question mark (?) in the following questions?

How many natural numbers divisible by 7 are there between 3 and 200? 

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

Find the sum of 30²+31²+32²+________+80²

Direction : What value should come in the place of question mark (?) in the following questions?

The number which can be written in the form of n (n+1) (n+2), where n is a natural number, is: