Question

Find the no. Between 1 to 201 which are divisive by 5

Answer 1

So take it as in AP

the series starts with 5 and ends with 200

since 5 and 200 are divisible by 5

in AP a,a+d,a+2d.......+(a+(n-1)d)

a= first number d= common difference ===> d=5 (since it is divisible by 5)

a=5 and an=200

an= a+(n-1)d = 200

5+(n-1)5=200

5+5n-5=200

5n=200

n=200/5

n=40

The total numbers between 1 and 201 divisible by 5 are 40

starting with 5,10,15,20,25,.......,200