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To find the sum of the first 81 odd numbers, we can use the formula for the sum of an arithmetic series: Sn = n/2 * (2a + (n-1)d), where n is the number of terms, a is the first term, and d is the common difference. In this case, n = 81, a = 1 (first odd number), and d = 2 (since the difference between consecutive odd numbers is 2). Plugging these values into the formula, we get: S81 = 81/2 * (2(1) + (81-1)2) = 81/2 * (2 + 160) = 81/2 * 162 = 6561. Therefore, the sum of the first 81 odd numbers is 6561.

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ProfBot

5mo ago

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