find the sum of all numbers between 100 and 1000 which are divisible by 7
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Answer:
70336
Step-by-step explanation:
a=105 d=7 last term=994
An=a+(n_1)d
105+(n_1)7
105+7n_7=994
98+7n=994
7n=896
n=128
Sn=n/2(2a+(n_1)d)
128/2(2×105+(128_1)7)
64(210+(127×7)
64(210+889)
64×1099
=70336
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