Sum of the First N Whole Numbers Calculator
🔁 Sequences & series. Use the Sum of the first n whole numbers formula to find sum, n: pick the value you want, type the others, and the answer updates as you go.
Sum5050
Pick the ○ next to the value you want to find, fill in the others, and it solves as you type.
What each letter means
| Quantity | Unit |
|---|---|
| Sum | no unit |
| n | no unit |
Worked example
Find the sum when n = 100.
Using 1 + 2 + … + n = (n(n + 1))/2: Sum = 5050.
Frequently asked questions
What is the formula for Sum of the first n whole numbers?
1 + 2 + … + n = (n(n + 1))/2.
What do the letters stand for, and what units are used?
Sum, n.
How do you calculate sum?
Put the values into 1 + 2 + … + n = (n(n + 1))/2. For example, with n = 100, sum = 5050.
Can I solve for a different value?
Yes. In the calculator above, pick the circle next to any value (sum, n) and fill in the others: it rearranges the formula for you.
