Question

Find sum of all natural no. That are less then 100 and divisible by 4

Answer 1

a=4
d=4
an=96
we know that
an =a+(n-1)d
96=4+(n-1) 4
96-4/4= n-1
43+1 =n
n=44

sn =n/2(2a + (n-1)d
sn=22(8+43.4)
sn=22.180
sn=3960

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