FIND THE SUM OF ALL THE POSITIVE INTEGER LESS THAN 200 THATHAT ARE DIVISIBLE BY 3 BUT NOT BY 7
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first no. divisible by 3 = 3
last number= 198
so, AP:- 3 , 6, 9, .. ..... ... . ,198
as, An = a +(n-1)d
and here d = 6-3
d = 3
so, An = 3 +(n-1) 3
198 =3 +(n-1)3
198-3 = (n-1)3
195 / 3 = n-1
65 +1 = n
66 = n..
now, S66 = n/2 (a +An)
S66 = 66/2 (3+198)
S66 = 33 * 201
S66 = 6633
last number= 198
so, AP:- 3 , 6, 9, .. ..... ... . ,198
as, An = a +(n-1)d
and here d = 6-3
d = 3
so, An = 3 +(n-1) 3
198 =3 +(n-1)3
198-3 = (n-1)3
195 / 3 = n-1
65 +1 = n
66 = n..
now, S66 = n/2 (a +An)
S66 = 66/2 (3+198)
S66 = 33 * 201
S66 = 6633
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