Question

Find the sum of all two digit numbers which are not divisible by five

Answer 1

Answer:

4200

Step-by-step explanation:

we know last two digit no. divisible by 5 is 95. So remove all the number divisible by 5 by dividing 95 by 5 and subtracting quotient from last two digit number 99.

we get,

a=10     d=5    l=95    n=80

sₙ=n/2(a+l)

sₙ=80/2(10+95)

sₙ=40×105

sₙ=4200