Question

what is the sum of first five natural numbers divisible by 5​

Answer 1

Answer:

Even natural numbers: 2,4,6,8,10,....

Even natural numbers divisible by 5→10,20,30,40,.... to 100 terms

Here, a=10,d=20−10=10, and n=100

We have,

S

n

=n/2(2a+(n−1)d)

=100/2[2×10+(100−1)10]

=50500.

Answer 2

Answer:

sn=150

Step-by-step explanation:

d=2×5=10

a = 10

an= 10,20,30,40,50...

a5=a+(n-1)d

a5=10+(5-1)10

a5=10+4×10

a5=50

sum of first five even numbers divisible by 5=

sn=n/2 (a+l)

s5=5/2 (10+50)

s5=5/2×60

s5=5×30

s5=150

thus sum of first five even numbers divisible by 5 is 150