find the sum of all two digit positive numbers divisible by 3
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2 digit no. divisble by 3 are 12,15,18,21..............99
so , a=12 d=3 an=99
an = a + (n-1)d
99 = 12 + (n-1) 3
99-12 = (n-1) 3
87/3 = (n-1)
29 +1 =n
n= 30
Sn = n/2 (a+l)
= 30/2 (12 + 99)
= 15 * 111
= 1665
so , a=12 d=3 an=99
an = a + (n-1)d
99 = 12 + (n-1) 3
99-12 = (n-1) 3
87/3 = (n-1)
29 +1 =n
n= 30
Sn = n/2 (a+l)
= 30/2 (12 + 99)
= 15 * 111
= 1665
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