Question

find the sum of all three digit no. which is divisible by 2 and 5
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Answer 1

Step-by-step explanation:

First of all all the nos with 0 at ones place will be divisible by both 2 and 5.

So our AP will be :

100,110,120,130________________990

an = 990

a = 100

d = 10

Sn = ?

n = ?

an = a + (n-1)d

990 = 100 + ( n - 1)10

990-100 = (n-1)10

880/10 = n - 1

88 + 1 = n

89 = n

Sn = (89/2)[2(100) + (89-1)10]

= (89/2)(200 + 880)

=(89/2)1080

=48060