Find the sum of all 3 digit number which when divided by 7 leaves remainder 4
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Step-by-step explanation:
it makes a A.p = 102,109,116,123......998
an=998,a=102, d= 109-102=7
number of terms = an=a+(n-1)d
998=102+(n-1)×7
998-102 =( n-1)7
896=( n-1)×7
896/7=(n-1)
128= n-1
n=128+1
n=129
sum of all terms(sn)= n/2 (a+ an)
= 129/2 (102+998)
= 129/2 × 1100
= 70950answer
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