Calculator

Using the basic calculator accurately

This calculator supports everyday arithmetic: addition, subtraction, multiplication, division, percentages, sign changes and decimal values. Enter one operation at a time or use the keyboard shortcuts shown above. The history helps you review the sequence instead of relying on memory.

Order of operations matters when a calculation contains several steps. Parentheses are evaluated first, followed by exponents when supported, multiplication and division, then addition and subtraction. Operations at the same level are handled from left to right. When a result is important, break a long expression into understandable parts and review each part.

Worked tip example

To calculate a 15% tip on $48, multiply 48 × 0.15 = 7.20. Add 48 + 7.20 for a total of $55.20. To split the total among three people, divide 55.20 ÷ 3 = 18.40.

Working with percentages

“Percent” means per hundred. Convert 7% to the decimal 0.07 before multiplying. To find percentage increase, subtract the old value from the new value, divide by the old value and multiply by 100. A 20% discount is not reversed by adding 20% afterward because the second percentage uses a smaller base.

Displayed decimals may be rounded even when the internal result contains more digits. For money, round the final result according to the currency’s smallest unit, usually cents. For measurements, keep enough significant digits for the purpose and avoid implying more precision than the original data supports.

Common mistakes

Entering 8% as 8 instead of 0.08 when manually multiplying.
Forgetting parentheses in an expression such as (10 + 5) × 2.
Rounding every intermediate result instead of the final result.
Assuming division by zero has a numeric answer; it is undefined.

Check important calculations

Estimate the expected size of an answer before accepting it. If 19 items cost about $5 each, the total should be close to $100; a displayed result near $1,000 suggests an input or decimal error. Recalculate important work in a second way, such as reversing an operation or using a simplified estimate. Save the units with the result because a correct number without dollars, feet, hours or another label can still be misunderstood. For taxes, contracts, medication, engineering or regulated reporting, follow the official method and obtain qualified review.

Frequently asked questions

Why does 0.1 + 0.2 sometimes display a long decimal? Computers approximate many decimal fractions in binary; the interface rounds ordinary results.

What does AC do? All Clear resets the expression and result.