find the sum of all two-digit natural numbers which when divided by 4 yields 2 as remainder.

Asked by deepitapai | 26th Jan, 2009, 08:08: AM

Expert Answer:

The first such natural number is 6.Note that all such numbers will have a gap of 4 between them.

So the numbers are 6,10,14..

 the last two digit number is 98

So sum of all these numbers is the sum of A.P.

6+10+14+...98

This A.P.  clearly has 24 terms.

So, use the formula for sum of n terms of an A.P. with first term=a=6

common difference =d=4

number of terms =n=24

So you can get the answer using the formula for sum of n terms

={n/2}{2a+(n-1)d}

Answered by  | 26th Jan, 2009, 01:03: PM

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