According to this question, any number between 1 to 100 should be divisible by 2 or 5 but not by 2×5=10. Possible numbers between 1 to 100 divisible by 2 are 2,4,6,....,100 This is an A.P where first term =2, last term =100 and total terms =50. ∴ Sum of the numbers divisible by 2 =‌
50
2
[2+100] =25×102 =2550 Possible numbers between 1 to 100 divisible by 5 are 5,10,15,....,100 ∴ Sum of the numbers divisible by 5 =‌
20
2
[5+100] =10×105 =1050 And possible numbers between 1 to 100 divisible by 10 are 10,20,30,....,100 ∴ Sum of the numbers divisible by 10 =‌
10
2
[10+100] =5×110 =550 ∴ Required sum =2550+1050−550=3050