Question

The sum of first 10 odd numbers​

Answer 1

Answer:

100

Step-by-step explanation:

1st way,

1, 3, 5, _________

This series is in Arithmetic Progression

a (first term) = 1

d (common difference) = 3-1 = 2

n = 10

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

S10 = 10/2 [2×1 + (10-1)2]

= 5 [2 + 9×2]

= 5 ( 2 + 18)

= 5 × 20

= 100

2nd way,

First 10 odd numbers

1, 3, 5, 7, 9, 11, 13, 15, 17, 19

Their Sum

= 1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19

= 100

Answer 2

$\huge\tt\green{\underbrace{\overbrace{Solution}}} \\ \\ \textsf{Odd numbers :-} \\ \\ \textsf{The numbers like 1, 3, 5, 7, 9,} \\ \textsf{etc are odd numbers.} \\ \\ \textbf{Sum of first 10 odd numbers :-} \\ \\ \textsf{1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19} \\ \\ \textsf{We will rearrange it to make it easier :-} \\ \textsf{(19 + 1) + (17 + 3) + (15 + 5) + (13 + 7) + (11 + 9)} \\ \texttt{20 + 20 + 20 + 20 + 20} \\ \\ \textsf\purple{Answer :- 100} \\ \\ \textsf\red{Hope it will help you...}$