what is the sum of all 2 digit numbers which leave a remainder 3 when divided by 11
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Hey!!!!
let's form the AP first of all
=> 14 , 25 , 36 , .. 91
Thus
a = 14
d = 11
l = 91
n = ?
Thus l = a + (n - 1)d
=> 91 = 14 + (n - 1)11
=> (n - 1)11 = 77
=> n - 1 = 7
=> n = 8
Thus S8 = n/2 x (a + l)
=> S8 = 8/2(14 + 91)
=> S8 = 4 x 105
=> S8 = 420
Hope this helps
Note : This question is from optional exercise
let's form the AP first of all
=> 14 , 25 , 36 , .. 91
Thus
a = 14
d = 11
l = 91
n = ?
Thus l = a + (n - 1)d
=> 91 = 14 + (n - 1)11
=> (n - 1)11 = 77
=> n - 1 = 7
=> n = 8
Thus S8 = n/2 x (a + l)
=> S8 = 8/2(14 + 91)
=> S8 = 4 x 105
=> S8 = 420
Hope this helps
Note : This question is from optional exercise
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