What is the sum of odd numbers from 8 to 77? Here we will show you step-by-step how to calculate the sum of odd numbers from 8 to 77.
Step 1) We start by finding the first (F) and last (L) odd numbers from 8 to 77. It is easy to do that by simply looking at the numbers. The first odd number is 9, and the last odd number is 77.
F = 9
L = 77
Step 2) Next, we calculate the total odd numbers (T) there are from 8 to 77, using a formula. Here is the formula and the math:
T = (L - F + 2) ÷ 2
T = (77 - 9 + 2) ÷ 2
T = 70 ÷ 2
T = 35
Step 3) Finally, we use the information from Step 1 and Step 2, and another formula, to calculate the sum of odd numbers from 8 to 77, like this:
Sum = (T ÷ 2) × (2 × F + (2 × (T - 1))
Sum = (35 ÷ 2) × (2 × 9 + (2 × (35 - 1))
Sum = 17.5 × (18 + 68)
Sum = 17.5 × 86
Sum = 1505
Sum of odd numbers from 8 to 77 = 1505
Sum of Odd Numbers Calculator
Please use the tool below to calculate the sum of odd numbers for another set of numbers.