Addition Calculator

Enter the first number to add
Enter the second number to add
Math

The Addition Calculator adds two numbers together and shows the sum instantly. Enter any two values — whole numbers, decimals, or negatives — and it returns a + b along with the full equation.

Formula

Sum = a + b
  • The sum is the total you get when you combine two numbers.
  • Formula: Sum = a + b.
  • Both inputs accept decimals and negative numbers; adding a negative number is the same as subtracting.
  • The order of the two numbers does not change the result (addition is commutative).

Example Calculation

Inputs
  • First Number: 15
  • Second Number: 25

Adding 15 and 25 gives a sum of 40: 15 + 25 = 40.

Frequently asked questions

What does the Addition Calculator do?
It adds the two numbers you enter and returns their sum, a + b, along with the full equation.
Can I add decimals and negative numbers?
Yes. Both fields accept decimals and negatives. Adding a negative number is the same as subtracting its absolute value.
Does the order of the numbers matter?
No. Addition is commutative, so a + b gives the same result as b + a.
How precise is the result?
The sum is exact; only the displayed value is rounded for readability, up to 8 decimal places.
Can I add more than two numbers?
This calculator adds two numbers at a time. To add several, sum the first two, then add the next to that running total.