Question

find sum of all three digit number which are divisible by 23 ​

Answer 1

Step-by-step explanation:

by using ap formula n = ?, a= 115( because 3 digit no starts from 115) D =23 (because difference depends on the no from which we divide)

an =989 last 3 digit term of 23

an = a+(n-1)d

989= 115+(n-1)23

989=115+23n-23

989=92+23n

989-92=23n

897=23n

897/23=n

n=39

this n says that 39 terms are 3digit if multiply by 23

to find the sum of them

sn = n/2(2a+(n-1)d)

sn= 39/2[2(115)+(38)23]. sn means sum of the 39 terms

sn=39[115+874]

sn = 39[989]

sn =38571

The sum of 3 digit no divisible 23 are 38571