What is the sum of even numbers from 18 to 39? Here we will show you step-by-step how to calculate the sum of even numbers from 18 to 39.
Step 1) We start by finding the first (F) and last (L) even numbers from 18 to 39. It is easy to do that by simply looking at the numbers. The first even number is 18, and the last even number is 38.
F = 18
L = 38
Step 2) Next, we calculate the total even numbers (T) there are from 18 to 39, using a formula. Here is the formula and the math:
T = (L - F + 2) ÷ 2
T = (38 - 18 + 2) ÷ 2
T = 22 ÷ 2
T = 11
Step 3) Finally, we use the information from Step 1 and Step 2, and another formula, to calculate the sum of even numbers from 18 to 39, like this:
Sum = (T ÷ 2) × (2 × F + (2 × (T - 1))
Sum = (11 ÷ 2) × (2 × 18 + (2 × (11 - 1))
Sum = 5.5 × (36 + 20)
Sum = 5.5 × 56
Sum = 308
Sum of even numbers from 18 to 39 = 308
Sum of Even Numbers Calculator
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