Math, asked by kotharinikki1914, 1 year ago

Find the sum of all natural number from 1 to 1000 which are not divisible by 5

Answers

Answered by karthik961
4

sum of first 'n' natural numbers =n(n+1)/2

sum of any 'n' numbers =n/2[1st term + last term]

sum of 1st 1000 natural numbers =1000×(1001)/2

=500500-----------------(1)

total number of 5 divisibles in 1-1000 is

1000/5=200 numbers

[5,10,15,......1000] is total 200 numbers

sum of all 5divisible is

[5+10+15+......+1000] =(200)/2×[5+1000]=100500----------(2)

{1st number is 5,last number is 1000,total numbers n=200}

(1)-(2)

we get ans = 400000

Similar questions