Math Calculator

Direct answer

A math calculator does the four basic operations — add, subtract, multiply and divide:

• Addition: 12 + 8 = 20
• Subtraction: 25 − 13 = 12
• Multiplication: 7 × 6 = 42
• Division: 84 ÷ 7 = 12

Enter your own two numbers below, pick the operation, and the tool shows the full expression and the result. The default on load is 12 + 8 = 20.

Inputs

Field	Default
First number	12
Operation	Add (+)
Second number	8

Outputs

Output	Default result
Full expression and result	Addition: 12 + 8 = 20

Defaults on load: 12, Add, 8 → 12 + 8 = 20. The tool shows this result before you type anything, and recalculates on every input change. Division by zero shows the message “Cannot divide by zero.” — never Infinity or NaN.

How it works

1. Pick the operation. Addition (+) combines, subtraction (−) takes away, multiplication (×) is repeated addition, and division (÷) splits into equal parts.
2. Enter two numbers. The tool uses exactly the numbers you type — whole numbers and decimals both work (for example, 12.5 + 8.25 = 20.75).
3. Read the full expression. The result line always shows the whole calculation, for example “Multiplication: 7 × 6 = 42”, so you can check the inputs as well as the answer.

Order of operations (BODMAS / PEMDAS)

When a calculation has more than one operation, do them in this order: Brackets first, then Orders (powers), then Division and Multiplication (left to right), then Addition and Subtraction (left to right). PEMDAS is the same rule with American names: Parentheses, Exponents, Multiplication, Division, Addition, Subtraction.

Example: 6 + 2 × 3 = 12, because multiplication comes first — 2 × 3 = 6, then 6 + 6 = 12. Working left to right instead would give the wrong answer, 24. The same order of operations applies when you work with parts of a whole: the percentage calculator handles percent problems, and the fraction calculator adds, subtracts, multiplies and divides fractions step by step. Brackets change the order: (6 + 2) × 3 = 24, because the brackets are done first — 6 + 2 = 8, then 8 × 3 = 24.

Operation symbols and meanings

Operation	Symbol	Meaning	Example
Addition	+	Combine two numbers into a total	12 + 8 = 20
Subtraction	−	Take the second number away from the first	25 − 13 = 12
Multiplication	×	Add a number to itself a number of times	7 × 6 = 42
Division	÷	Split the first number into equal parts	84 ÷ 7 = 12

Times-table reference for the default example (8 times table)

The default calculation is 12 + 8 = 20. The number 8 also appears in the 8 times table, which is useful for checking multiplication by 8:

×	1	2	3	4	5	6	7	8	9	10
8 ×	8	16	24	32	40	48	56	64	72	80

Worked examples (all recomputed)

Example 1 — Addition (the default): 12 + 8 = 20

• 12 + 8 = 20
• Check by counting on: 12, then 8 more — 13, 14, 15, 16, 17, 18, 19, 20.
• Check by subtraction: 20 − 8 = 12, which is the first number back.

Example 2 — Subtraction: 25 − 13 = 12

• 25 − 13 = 12
• Check by addition: 12 + 13 = 25, which is the starting number back.

Example 3 — Multiplication: 7 × 6 = 42

• 7 × 6 = 42
• As repeated addition: 6 + 6 + 6 + 6 + 6 + 6 + 6 = 42
• Check by division: 42 ÷ 7 = 6, which is the second number back.

Example 4 — Division: 84 ÷ 7 = 12

• 84 ÷ 7 = 12
• Check by multiplication: 12 × 7 = 84, which is the starting number back.
• A second division check: 100 ÷ 4 = 25.

Tips and mistakes

• Do the multiplication and division before addition and subtraction. 6 + 2 × 3 is 12, not 24 — see the order-of-operations section above.
• Never divide by zero. 12 ÷ 0 has no answer. The tool says so plainly instead of showing Infinity; change the second number to anything except 0.
• Check a subtraction with addition, and a division with multiplication. If 25 − 13 = 12, then 12 + 13 must be 25. If 84 ÷ 7 = 12, then 12 × 7 must be 84.
• Keep the decimal point lined up. 12.5 + 8.25 = 20.75 — adding 12.5 + 8.25 as if they were 125 + 825 gives the wrong answer.
• Watch the order in subtraction and division. 25 − 13 = 12, but 13 − 25 = −12; 84 ÷ 7 = 12, but 7 ÷ 84 = 0.08. Swapping the numbers changes the answer, unlike addition and multiplication.

Sources

Arithmetic follows standard definitions — see the NIST Digital Library of Mathematical Functions. Reviewed by the Average Calculator Team. Last reviewed: 7 November 2026.

FAQs

How do you add two numbers?

Add the second number to the first: the sum is the total of both numbers. For example, 12 + 8 = 20. Enter both numbers in the tool above, choose Add (+), and it shows the full expression and the result.

How do you subtract one number from another?

Take the second number away from the first: the difference is what is left. For example, 25 − 13 = 12. Check it by adding: 12 + 13 = 25, which is the starting number back.

What is 12 plus 8?

12 plus 8 equals 20. That is the default calculation on this page: the tool loads with 12, Add (+), and 8, and shows “Addition: 12 + 8 = 20” before you type anything.

How do you multiply two numbers?

Multiply the first number by the second: multiplication is repeated addition. For example, 7 × 6 = 42, which is 6 added to itself 7 times. Check it by dividing: 42 ÷ 7 = 6.

How do you divide one number by another?

Split the first number into equal parts of the second number’s size. For example, 84 ÷ 7 = 12, because 7 groups of 12 make 84. You cannot divide by zero — the tool shows “Cannot divide by zero.” instead of an answer.

What is the order of operations (BODMAS / PEMDAS)?

Do brackets first, then powers, then multiplication and division from left to right, then addition and subtraction from left to right. For example, 6 + 2 × 3 = 12, because 2 × 3 = 6 is done first and then 6 + 6 = 12. Brackets change the order: (6 + 2) × 3 = 24.

Disclaimer

Results depend on the numbers you enter. This page is an educational arithmetic tool for everyday calculations; double-check the result before using it for anything important, such as money, measurements or schoolwork submitted for grading.

Related calculators

• Average Calculator Online — the homepage average tool
• Scientific Calculator — powers, roots and trigonometry beyond basic arithmetic
• Percentage Calculator — percentage change and percentages of a number
• Fraction Calculator — add, subtract, multiply and divide fractions
• Volume Calculator — volume of boxes, cylinders and spheres

Last updated: November 7, 2026.