Sum of the first 18 Odd Numbers

n	O_n
1	1
2	3
3	5
4	7
5	9
6	11
7	13
8	15
9	17
10	19
11	21
12	23
13	25
14	27
15	29
16	31
17	33
18	35

What is the Answer?

S₁₈ = 324
Average (A) of the first 18 Odd Numbers = 18

How does the Sum of the First (n) Numbers Calculator work?

Free Sum of the First (n) Numbers Calculator - Determines the sum of the first (n)
* Whole Numbers
* Natural Numbers
* Even Numbers
* Odd Numbers
* Square Numbers
* Cube Numbers
* Fourth Power Numbers
This calculator has 1 input.

What 7 formulas are used for the Sum of the First (n) Numbers Calculator?

Sum of the first n whole numbers = n(n - 1)/2
Sum of the first n natural numbers = n(n - 1)/2
Sum of the first n even numbers = n(n - 1)
Sum of the first n odd numbers = n²
Sum of the first n square numbers = n(n + 1)(2n + 1)/6
Sum of the first n cube numbers = n²(n + 1)²/4
Sum of the first n fourth power numbers = n(n + 1)(2n + 1)(3n² + 3n - 1)/30

For more math formulas, check out our Formula Dossier

What 7 concepts are covered in the Sum of the First (n) Numbers Calculator?

even number: a whole number that is able to be divided by two into two equal whole numbers
integer: a whole number; a number that is not a fraction
...,-5,-4,-3,-2,-1,0,1,2,3,4,5,...
natural number: the positive integers (whole numbers)
1, 2, 3, ...
odd number: a whole number that is not able to be divided by two into two equal whole numbers
sum: the total amount resulting from the addition of two or more numbers, amounts, or items
sum of the first (n) numbers
whole number: numbers that include natural numbers and zero
{0, 1, 2, 3, ...}

Sum of the first 18 Odd Numbers

Σ n Odd Numbers formula:

Average (A) of the first 18 Odd Numbers