What is the sum of odd numbers from 60 to 90? Here we will show you step-by-step how to calculate the sum of odd numbers from 60 to 90.
Step 1) We start by finding the first (F) and last (L) odd numbers from 60 to 90. It is easy to do that by simply looking at the numbers. The first odd number is 61, and the last odd number is 89.
F = 61
L = 89
Step 2) Next, we calculate the total odd numbers (T) there are from 60 to 90, using a formula. Here is the formula and the math:
T = (L - F + 2) ÷ 2
T = (89 - 61 + 2) ÷ 2
T = 30 ÷ 2
T = 15
Step 3) Finally, we use the information from Step 1 and Step 2, and another formula, to calculate the sum of odd numbers from 60 to 90, like this:
Sum = (T ÷ 2) × (2 × F + (2 × (T - 1))
Sum = (15 ÷ 2) × (2 × 61 + (2 × (15 - 1))
Sum = 7.5 × (122 + 28)
Sum = 7.5 × 150
Sum = 1125
Sum of odd numbers from 60 to 90 = 1125
Sum of Odd Numbers Calculator
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