Question

Question 14
Find the sum of the odd numbers between 0 and 50.

Answer 1

The odd numbers between 0 and 50 are;
1, 3, 5, 7, 9 … 49
Therefore, it can be observed that these odd numbers are in an A.P.
a = 1
d = 2
l = 49
l = a + (n − 1) d
49 = 1 + (n − 1)2
48 = 2(n − 1)
n − 1 = 24
n = 25
$S_n=\frac{n}{2}(a+l)S_{25}=\frac{25}{2}(1+49)=\frac{25\left(50\right)}{2}=\left(25\right)\left(25\right)=625$