Question

How many numbers between 200 and 700 are divisible by 15? Find their sum.

Answer 1

Between 200 and 700,210 is divisible by 15

a=210

an=675

d=15

an=a+(n-1)d

675=210+(n-1)15

675-210=15(n-1)

465=15(n-1)

465/15=n-1

31=n-1

32=n