Question

The sum of all two digit numbers between 2 and 100 and is divisible by three is ?

Answer 1

Step-by-step explanation:

From 1 to 100,all numbers are either divisible by 2 or by 3 except

(a) All

Prime numbers (excluding 2)

(b) Number 1 (not coming under calculations )

So in order to have the sum of all numbers divisible either by 2 or 3 First we have to get the sum of all Prime numbers & sum of all numbers from 2 to 100,then we will subtract the former from the latter to arrive at the ANSWER.

SUM OF ALL PRIME NUMBERS = 1058

SUM OF NUMBERS 1 TO 100

{(100)*(100+1)}/2=5050

5050–1= 5049

ALL NUMBERS FROM 1 TO 100 DIVISIBLE BY 2 OR 3=5049 -1058=3991 ANSWER

List of 25 Prime numbers from 1 to 100

2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89&97

I suppose there is no formula to add all prime numbers within a certain range of number.