Find the sum of all numbers between 100 and 200 which are divisible by 5
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The list of numbers between 100 and 200 divisible by 5 are,
105, 110, 115,120,......195.
The above list in AP wit a=105, d=5, and an=195.
an=a+(n-1)d
105+(n-1)5=195
(n-1)5=90
n-1=18
n=18-1=17
ie,n=17//
Sn=n/2[2a+(n-1)d]
S24=17/2[2(105)+(17-1)5)]
=17/2[210+16*5]
=17/2[210+80]
=17/2[290]
=17*145
=2465//
105, 110, 115,120,......195.
The above list in AP wit a=105, d=5, and an=195.
an=a+(n-1)d
105+(n-1)5=195
(n-1)5=90
n-1=18
n=18-1=17
ie,n=17//
Sn=n/2[2a+(n-1)d]
S24=17/2[2(105)+(17-1)5)]
=17/2[210+16*5]
=17/2[210+80]
=17/2[290]
=17*145
=2465//
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