What is the sum of odd numbers from 10 to 72? Here we will show you step-by-step how to calculate the sum of odd numbers from 10 to 72.
Step 1) We start by finding the first (F) and last (L) odd numbers from 10 to 72. It is easy to do that by simply looking at the numbers. The first odd number is 11, and the last odd number is 71.
F = 11
L = 71
Step 2) Next, we calculate the total odd numbers (T) there are from 10 to 72, using a formula. Here is the formula and the math:
T = (L - F + 2) ÷ 2
T = (71 - 11 + 2) ÷ 2
T = 62 ÷ 2
T = 31
Step 3) Finally, we use the information from Step 1 and Step 2, and another formula, to calculate the sum of odd numbers from 10 to 72, like this:
Sum = (T ÷ 2) × (2 × F + (2 × (T - 1))
Sum = (31 ÷ 2) × (2 × 11 + (2 × (31 - 1))
Sum = 15.5 × (22 + 60)
Sum = 15.5 × 82
Sum = 1271
Sum of odd numbers from 10 to 72 = 1271
Sum of Odd Numbers Calculator
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