Find the sum of all multiples of 7 line between hundred and thousand
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Answer:
70,336
Step-by-step explanation:
A.P.=105,112,119,.........994
a=105 d=7 an=994
an= (a+(n-1)d)
994=(105+(n-1)7)
994-105=7n-7
889=7n-7
889+7=7n
896=7n
n=128
Sn=n/2 (2a+(n-1)d)
S128=128/2 (2 (105)+(128-1)7)
S128=64 (210+(127)7)
S128=64 (210+889)
S128= 64 (1099)
S128=70336
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