What is the sum of odd numbers from 20 to 133? Here we will show you step-by-step how to calculate the sum of odd numbers from 20 to 133.
Step 1) We start by finding the first (F) and last (L) odd numbers from 20 to 133. It is easy to do that by simply looking at the numbers. The first odd number is 21, and the last odd number is 133.
F = 21
L = 133
Step 2) Next, we calculate the total odd numbers (T) there are from 20 to 133, using a formula. Here is the formula and the math:
T = (L - F + 2) ÷ 2
T = (133 - 21 + 2) ÷ 2
T = 114 ÷ 2
T = 57
Step 3) Finally, we use the information from Step 1 and Step 2, and another formula, to calculate the sum of odd numbers from 20 to 133, like this:
Sum = (T ÷ 2) × (2 × F + (2 × (T - 1))
Sum = (57 ÷ 2) × (2 × 21 + (2 × (57 - 1))
Sum = 28.5 × (42 + 112)
Sum = 28.5 × 154
Sum = 4389
Sum of odd numbers from 20 to 133 = 4389
Sum of Odd Numbers Calculator
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