What is the sum of odd numbers from 20 to 135? Here we will show you step-by-step how to calculate the sum of odd numbers from 20 to 135.
Step 1) We start by finding the first (F) and last (L) odd numbers from 20 to 135. It is easy to do that by simply looking at the numbers. The first odd number is 21, and the last odd number is 135.
F = 21
L = 135
Step 2) Next, we calculate the total odd numbers (T) there are from 20 to 135, using a formula. Here is the formula and the math:
T = (L - F + 2) ÷ 2
T = (135 - 21 + 2) ÷ 2
T = 116 ÷ 2
T = 58
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 135, like this:
Sum = (T ÷ 2) × (2 × F + (2 × (T - 1))
Sum = (58 ÷ 2) × (2 × 21 + (2 × (58 - 1))
Sum = 29 × (42 + 114)
Sum = 29 × 156
Sum = 4524
Sum of odd numbers from 20 to 135 = 4524
Sum of Odd Numbers Calculator
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