What is the sum of odd numbers from 11 to 30? Here we will show you step-by-step how to calculate the sum of odd numbers from 11 to 30.
Step 1) We start by finding the first (F) and last (L) odd numbers from 11 to 30. It is easy to do that by simply looking at the numbers. The first odd number is 11, and the last odd number is 29.
F = 11
L = 29
Step 2) Next, we calculate the total odd numbers (T) there are from 11 to 30, using a formula. Here is the formula and the math:
T = (L - F + 2) ÷ 2
T = (29 - 11 + 2) ÷ 2
T = 20 ÷ 2
T = 10
Step 3) Finally, we use the information from Step 1 and Step 2, and another formula, to calculate the sum of odd numbers from 11 to 30, like this:
Sum = (T ÷ 2) × (2 × F + (2 × (T - 1))
Sum = (10 ÷ 2) × (2 × 11 + (2 × (10 - 1))
Sum = 5 × (22 + 18)
Sum = 5 × 40
Sum = 200
Sum of odd numbers from 11 to 30 = 200
Sum of Odd Numbers Calculator
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