22Using AP, find the sum of all 3-digit natural numbers which are the

1.	22Using AP, find the sum of all 3-digit natural numbers which are the multiples of 7.
Answer» Smallest three digit number divisible by 7 = 105 and the largest = 994An = 994A = 105D = 7n= ?An = A + [ n - 1] Dthus994 = 105 + [ n - 1 ] 7thus by solving furthern = 128 now,Sn = n/2 [ A + An] Sn = 128/2 [ 105 + 994]thus,Sn = 70336.Thus the sum of all the three digit numbers divisible by 7 is 70336.

22Using AP, find the sum of all 3-digit natural numbers which are the multiples of 7.

Answer»

Smallest three digit number divisible by 7 = 105 and the largest = 994An = 994A = 105D = 7n= ?An = A + [ n - 1] Dthus994 = 105 + [ n - 1 ] 7thus by solving furthern = 128

now,Sn = n/2 [ A + An]

Sn = 128/2 [ 105 + 994]thus,Sn = 70336.Thus the sum of all the three digit numbers divisible by 7 is 70336.

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22Using AP, find the sum of all 3-digit natural numbers which are the multiples of 7.

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