The sum of first 45 natural numbers is -

Question: The sum of first 45 natural numbers is -Solution:Let Sn =(1 + 2 + 3 + ... + 45). This is an A.P. in which a =1, d =1, n = 45. Sn = (n/2)[2a + (n - 1)d]= (45/2) × [2 × 1 + (45 - 1) × 1]= (45/2) × 46= (45 × 23)= 1035বিকল্প সমাধান:Sn = {n(n + 1)}/2 = {45(45 + 1)}/2 = 1035