Find all the 2 digit numbers which are divisible by 3. Also Also find their Sun.
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Step-by-step explanation:
First two digit number divisible by 3 = 12
Last two digit number divisible by 3 = 99
∴ First term, (a)=12
Common difference, (d)=3
Last term, (l)=99
n=?
As we know that,
an =a+(n−1)d
∴99=12+(n−1)3
⇒(n−1) 87/3
⇒n=29+1=30
∴ Sum of n terms of an A.P., when last term is known is given by-
Sn=n/2(a+l)
∴S30= 30/2(12+99)
⇒S30=15×111=1665
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