find the sum of all 3 digit numbers which are divisible by 7
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Sum of all 3 digits numbers which are divisible by 7
105 , 112 , 119, ................., 994
a: 105
d: 112 - 105
: 7
n: ?
sum : ???
t(n) : 994
t(n) : a + (n-1) d
994 : 105 + (n - 1) 7
994 - 105 : (n - 1) 7
889 : (n - 1) 7
889/ 7 : (n - 1)
(n - 1) : 127
n: 127+1
n: 128
s(n)= n/ 2 [2a + ( n -1) d]
s(128) = 128/2 [2(105) + (128-1) 7]
= 64 [210 + (127)7]
= 64[ 210 + 889]
= 64( 1099)
= 70336
May it is helpful for you.
✌✌✌Have a great day ✌✌✌
Good morning
Sum of all 3 digits numbers which are divisible by 7
105 , 112 , 119, ................., 994
a: 105
d: 112 - 105
: 7
n: ?
sum : ???
t(n) : 994
t(n) : a + (n-1) d
994 : 105 + (n - 1) 7
994 - 105 : (n - 1) 7
889 : (n - 1) 7
889/ 7 : (n - 1)
(n - 1) : 127
n: 127+1
n: 128
s(n)= n/ 2 [2a + ( n -1) d]
s(128) = 128/2 [2(105) + (128-1) 7]
= 64 [210 + (127)7]
= 64[ 210 + 889]
= 64( 1099)
= 70336
May it is helpful for you.
✌✌✌Have a great day ✌✌✌
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Answered by
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Hope it will help you
sum is 70336
sum is 70336
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