Question

Find the sum of all numbers from 1 to 59

Answer 1

an = a+(n-1)d
59 = 1 +(n-1)1
59-1 = n-1
58 =n-1
n = 59

Now,
Sn = n/2 (a+an)
= 59/2 (1+59)
= 59/2 (60)
= 59 (30)
= 1770

Therrfore, sum of al no. is 1770