Basic Calculator
A basic calculator adds, subtracts, multiplies and divides numbers. Type an expression such as 128 × 1.2 + 15 and the answer appears as you type. Multiplication and division are worked out before addition and subtraction, so 2 + 3 × 4 = 14. Use the keypad or your keyboard.
How to use the Basic Calculator
- Type numbers and operators with the keypad or your keyboard (0-9, +, -, *, /, %).
- Watch the result update under the expression as you type.
- Press = or Enter to keep the answer and continue calculating from it.
- Press ⌫ or Backspace to delete the last entry, and AC or Escape to start over.
Formula
Order of operations: brackets, then × and ÷ left to right, then + and - left to rightThe calculator evaluates the whole expression using standard precedence (PEMDAS/BODMAS). A percent sign divides a number by 100, and after + or - it takes that percentage of the running total, so 200 + 15% = 230.
How the percent key works
- 200 × 15% = 30, because 15% means 0.15.
- 200 + 15% = 230, because the 15% is taken of 200 and added.
- 200 - 15% = 170, the usual way to apply a discount.
- 50% on its own = 0.5.
Keyboard shortcuts
- Digits 0-9 and the decimal point enter numbers.
- + and - add and subtract; * or x multiplies; / divides.
- Enter or = shows the final answer.
- Backspace deletes the last character; Escape or Delete clears everything.
- ( and ) group parts of a calculation.
Worked example
To work out (15 + 8) × 3, type ( 15 + 8 ) × 3. The display shows 69. Without brackets, 15 + 8 × 3 gives 39, because the multiplication happens first.
Basic Calculator questions
How do I perform basic arithmetic on this calculator?
Type the full calculation, for example 15 + 27, and the answer (42) appears straight away. Press = or Enter to keep the result and continue from it. You can chain operations such as 15 + 27 × 2, and the calculator applies standard order of operations, giving 69.
Does the calculator follow the order of operations?
Yes. Brackets are evaluated first, then multiplication and division from left to right, then addition and subtraction from left to right. For example, 2 + 3 × 4 = 14, while (2 + 3) × 4 = 20. Use brackets whenever you want a different order.
How precise are the results?
Results are rounded to 12 significant digits and shown with up to 10 decimal places, which is plenty for everyday, financial and school work. For example, 1 ÷ 3 shows 0.3333333333. Very large or very small answers switch to scientific notation, such as 1.5e13, so they stay readable.
How does the % key work?
A percent sign divides a number by 100. After multiplication it gives a share, so 80 × 25% = 20. After addition or subtraction it takes that percentage of the number before it, so 80 + 25% = 100 and 80 - 25% = 60, which is handy for tips and discounts.
What should I do if I make a mistake?
Press ⌫ (or Backspace) to remove the last digit or operator, or AC (or Escape) to clear everything. Because the expression stays on screen, you can see exactly what was entered and fix one character instead of retyping the whole calculation.
What happens if I divide by zero?
The calculator shows Error, because division by zero has no defined result. Press ⌫ to change the divisor or AC to start again. The same message appears for any expression that cannot be evaluated, such as an unmatched operator at the end.
Can I use my keyboard?
Yes. Digits, the decimal point, +, -, * and / work as you would expect, Enter or = gives the answer, Backspace deletes and Escape clears. Typing on a keyboard is usually faster than clicking for long calculations.
Should I use a calculator or do mental math?
Use mental math for quick estimates and simple sums, and a calculator for decimals, large numbers and multi-step problems. A good habit is to estimate first, then check with the calculator: if the two are far apart, one of the inputs is probably wrong.