Question

Find the sum of the first 20
positive odd integers.

Answer 1

Answer:

400

Step-by-step explanation:

first 20 positive odd integers are 1,3,5, ....39

if u observe carefully we hv 10 pairs whose sum is 40,

1 + 39

3+ 37

5+35

.

.

.

19+21

so sum is 40 × 10 =400

Answer 2

Answer:

first 20 positive odd numbers

1+3+5+7+9+11+13+15+17+19+21+23+25+27+29+31+33+35+37+39

= 400