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The sum of first 20 odd natural numbers is A. 100 B. 210 C. 400 D. 420 |
Answer» Here A.P is 1,3, 5, …… a= 1, d= 2 and n = 20 Sn = n/2(2a + (n–1) d) Sn = 20/2 (2 x 1 + (19) 2) Sn = 10 (2 + 38) Sn= 400 |
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