What is the sum of odd numbers from 2 to 78? Here we will show you step-by-step how to calculate the sum of odd numbers from 2 to 78.
Step 1) We start by finding the first (F) and last (L) odd numbers from 2 to 78. It is easy to do that by simply looking at the numbers. The first odd number is 3, and the last odd number is 77.
F = 3
L = 77
Step 2) Next, we calculate the total odd numbers (T) there are from 2 to 78, using a formula. Here is the formula and the math:
T = (L - F + 2) ÷ 2
T = (77 - 3 + 2) ÷ 2
T = 76 ÷ 2
T = 38
Step 3) Finally, we use the information from Step 1 and Step 2, and another formula, to calculate the sum of odd numbers from 2 to 78, like this:
Sum = (T ÷ 2) × (2 × F + (2 × (T - 1))
Sum = (38 ÷ 2) × (2 × 3 + (2 × (38 - 1))
Sum = 19 × (6 + 74)
Sum = 19 × 80
Sum = 1520
Sum of odd numbers from 2 to 78 = 1520
Sum of Odd Numbers Calculator
Please use the tool below to calculate the sum of odd numbers for another set of numbers.