Question

Find the sum :2+4+6+8+.......+200

Answer 1

2+4+6+8+......+200

=2 (1+2+3+4+..+100)

we know that sum formula

=n (n+1)/2

={2 ×100(100+1)/2}

=2×100×101/2

2 to 2 cancel

=100×101

=10100.

Answer 2

Answer:

10100

Step-by-step explanation:

last term(n)=200

Sn=n(n+1)/2

= 2+4+4+.........+200

=2(1+2+3+.....+100)

=2[100(100+1)/2]

=100×101

=10100