What is the sum of odd numbers from 121 to 199? Here we will show you step-by-step how to calculate the sum of odd numbers from 121 to 199.
Step 1) We start by finding the first (F) and last (L) odd numbers from 121 to 199. It is easy to do that by simply looking at the numbers. The first odd number is 121, and the last odd number is 199.
F = 121
L = 199
Step 2) Next, we calculate the total odd numbers (T) there are from 121 to 199, using a formula. Here is the formula and the math:
T = (L - F + 2) ÷ 2
T = (199 - 121 + 2) ÷ 2
T = 80 ÷ 2
T = 40
Step 3) Finally, we use the information from Step 1 and Step 2, and another formula, to calculate the sum of odd numbers from 121 to 199, like this:
Sum = (T ÷ 2) × (2 × F + (2 × (T - 1))
Sum = (40 ÷ 2) × (2 × 121 + (2 × (40 - 1))
Sum = 20 × (242 + 78)
Sum = 20 × 320
Sum = 6400
Sum of odd numbers from 121 to 199 = 6400
Sum of Odd Numbers Calculator
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