Question

Q.25. Find the sum of all natural numbers that are less than 100 and divisible by 4.
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Answer 1

Answer:

Sn=1200

The sum of all natural numbers that are less than 100 and divisible by 4 is 1200.

Step-by-step explanation:

The smallest natural numbr divisible by 4=4

The largest number inside 100 =96

Thus a=4

d=8-4=4

n=?

tn=96

tn=a+(n-1)d

96=4+(n-1)4

96-4=4n-4

92+4=4n

96=4n

n=96/4

n=24

You can directly find n by directly multiplying 96/4

Now,

Sn=n/2[2a+(n-1)d]

or

Sn=n/2(a+l)

Sn=24/2(4+96)

Sn=1200