SECTION - A
Find the sum of all natural numbers between 200 and 1000 exactly divisible by 7
Answers
Answered by
0
Step-by-step explanation:
The arithmetic series is, 204 + 210 + 216 + ...... + 294
∴a=204,d=210−204=6,Tn=294,Sn=?
To find Sn, we should first find the value of 'n'
Tn=294
a+(n−1)d=294
204+(n−1)6=294
204+6n−6=294
198+6n=294
6n=294−198=96
∴n=16
Sn=2n[a+Tn]
S16=216[204+294]=216×498=3984
Similar questions