Basic Calculator

Perform quick arithmetic instantly — addition, subtraction, multiplication, division, percentages, square roots, powers, memory functions, and random numbers. Full keyboard support and live calculation history.

Memory

Stored Value

History (0)

Calculations will appear here. Press = after typing an expression.

Common Examples

Tap any example to drop its result into the display — handy for quick reference.

What Is a Basic Calculator?

A basic calculator is a four-function arithmetic tool for everyday math — addition, subtraction, multiplication, and division. This online version adds percentages, square roots, powers, sign toggle, scientific-notation entry (EXP), four memory functions (M+, M−, MR, MC), a calculation history, and a random-number generator, while keeping the familiar one-tap-per-key layout of a desktop calculator.

Use it for shopping math, tip totals, exam preparation, lab measurements, quick conversions, and anywhere else you would reach for a handheld calculator. Pair it with the scientific calculator for trig and logarithms, the percentage calculator for percent change and reverse percent, and the scientific notation calculator for very large and very small numbers.

How the Calculator Works

Type a number

Tap digits 0–9, the decimal point, or ± to flip the sign. Use Back to erase one character at a time and AC to wipe the entry, accumulator, and pending operator in one press.

Chain operators

Tap +, −, ×, or ÷, then enter the next number. If you press another operator before pressing =, the calculator evaluates the pending operation first — the result becomes the new accumulator.

Apply functions

Single-operand keys — %, √, x², 1/x — act on the current display immediately. Percent is contextual: 200 + 10 % yields 20 (10 % of 200) so 200 + 10 % = 220, matching desktop-calculator convention.

Use memory

M+ adds the display to memory, M− subtracts, MR recalls the stored value into the display, and MC clears memory. A small M indicator above the keypad tells you when memory holds a non-zero value.

6 Ways to Use This Calculator

Shopping totals

Add prices, apply a discount with %, and figure tax in one expression: 79.99 + 14.50 − 10 % then + 8 % gives the post-discount, post-tax total. Press M+ at each store to roll the trip total in memory.

Tip & split bills

Compute 100 × 18 % for the tip, then divide the full bill by the headcount: (subtotal × 1.18) ÷ 4. Memory holds the per-person amount while you check who needs change.

Homework checks

Verify long-division and percent worksheets with one tap per digit. Square (x²) and square root (√) cover the perfect-square problems that show up in geometry and Pythagorean homework.

Lab measurements

Convert raw readings into averages, sums, and percent differences. EXP lets you enter scientific notation directly (e.g. 6.022 EXP 23) so chemistry constants stay precise.

Budget planning

Track monthly income and outflows by adding line items to memory with M+. MR shows the running total, M− removes a category, and MC resets when you start the next month.

Random sampling

Use the RND key to draw a uniform 0–1 number for quick raffles, dice substitutes, or to seed a worked example. Multiply by your range (e.g. RND × 100) for a 0–100 integer-ish pick.

Best Practices

Watch the expression preview. The small line above the main display shows the pending accumulator and operator. If it says200 +you know exactly which value the next number will be added to — no surprises when you press =.

Use Back instead of AC for typos. Back deletes one character at a time so you don't lose the pending operator. AC is the right move when you want to start a fresh calculation — it clears everything: display, accumulator, memory of the last operator, and any error state.

Use memory for running totals. M+ accumulates without interrupting the visible calculation. Add a shopping cart price, type the next item, press M+ again — the previous result is now safely stored. MR brings it back when you're ready to tax, tip, or compare.

Why a Basic Calculator Still Matters

Numeracy without distraction

A four-function layout puts arithmetic front and centre. There are no trig, log, or programming modes to wade through — you press a digit, an operator, and another digit, and the answer appears.

Memory does the heavy lifting

Storing a sub-total in M+ saves you from re-typing — a small habit that prevents the typos that creep in during long checkout receipts, recipe tripling, and exam reviews.

Keyboard support speeds you up

On a desktop, typing 12+34=, 5*7=, or 100/4= is faster than tapping. The calculator listens for digit, operator, Enter, Backspace, and Esc keys without any focus management on your part.

Reliable rounding

The display caps at 14 significant figures with proper rounding instead of truncation, then trims trailing zeros — so 1/3 stays 0.33333333333333 rather than dropping to a misleading 0.33.

Tricky Cases

Percent after + or −

When you press % after a + or − operator, the calculator reads it as 'X percent of the accumulator' — so 200 + 10 % equals 220, not 200.1. This matches every physical desktop calculator. After × or ÷, % is a plain divide-by-100.

Divide by zero

Division by 0 surfaces as 'Error' on the display and the next digit press starts a fresh entry. The error text below the screen explains what happened so you can fix the input — no silent NaN values to chase.

Chained operators

Pressing several operators in a row simply swaps the pending one without re-evaluating. So 5 + − = 5 (treats − as the new pending op). Tap a digit to add the right operand and = to finish.

Order of operations

Basic calculators evaluate left-to-right as you type — there's no implicit PEMDAS. To compute 2 + 3 × 4 with multiplication first, do 3 × 4 = 12, then + 2 = 14. The scientific calculator handles full PEMDAS with parentheses if you need it.

Core Operations

Addition

a + b

Combine two values. The accumulator stores a, the next number is b, = reveals a + b.

Subtraction

a − b

Subtract b from a. Pressing ± on either operand flips its sign and changes the result accordingly.

Multiplication

a × b

Scale a by b. Multiplying by % converts the second operand into a fraction first — 200 × 25 % = 50.

Division

a ÷ b, b ≠ 0

Split a into b equal parts. Dividing by 0 surfaces an error; the calculator never returns NaN or Infinity silently.

Percentage

a × p ÷ 100

% acts on the previous accumulator after + or −, and as plain ÷ 100 otherwise. So 80 × 25 % = 20 and 80 + 25 % = 100.

Square & root

x² , √x

x² returns x times x; √x is the non-negative square root. √ of a negative value surfaces an error.

Common Mistakes

Forgetting AC vs Back

AC clears the entire calculation — display, accumulator, pending operator. Back removes only the last digit. If you hit AC during a long chain you have to start over; Back lets you fix a single typo.

Assuming PEMDAS

On a basic calculator, 2 + 3 × 4 evaluates left-to-right to 20, not 14. If you need true order-of-operations, use the scientific calculator and type the expression with parentheses.

Mishandling percent

Pressing % expects context: after + or − it's 'percent of the running total'; after × or ÷ it's a plain divide-by-100. If a percent result looks wrong, check which operator you pressed first.

Trusting memory across sessions

Memory persists between page reloads but resets when you clear browser storage. Always M+ explicitly — values you simply leave in the display don't carry over.

Built for shoppers, students, teachers, lab assistants, small-business owners, and anyone who wants a clean four-function calculator without ads or signups. Every press updates the display and the expression preview, every result is recorded in history, and memory persists across page reloads — so you can pick up exactly where you left off.

Basic Calculator FAQs

A basic calculator handles the four core arithmetic operations — addition, subtraction, multiplication, and division — and on this page it also covers percent, square root (√), square (x²), reciprocal (1/x), sign toggle (±), and scientific-notation entry (EXP). You get four memory functions (M+, M−, MR, MC), a 30-entry calculation history, full keyboard support, and a random-number generator. For trigonometry, logarithms, factorials, or parentheses, switch to the scientific calculator.

M+ adds the current display to memory, M− subtracts the current display from memory, MR recalls the stored value into the display, and MC clears memory. A small 'M = …' indicator below the screen tells you when memory holds a non-zero value. Memory persists across page reloads via localStorage so you can pick up where you left off. Clear your browser data to reset it manually.

Yes — the % key is contextual. After + or −, it reads as 'X percent of the running total': 200 + 10 % gives 220 (10 % of 200 = 20, added to 200). After × or ÷, % is a plain divide-by-100: 80 × 25 % = 20. Pressing % with no operator active also divides by 100. This matches the convention used by Windows Calculator and every standard desktop calculator.

Yes. Digits 0–9 type directly, + − * / map to the four operators, . inserts a decimal point, % triggers the percent function, Enter (or =) evaluates, Backspace removes the last digit, and Esc clears the entire calculation (the same as AC). All shortcuts work without focusing any specific element — just have the page open.

Yes — the last 30 calculations are saved in your browser's local storage and shown in the History panel below the keypad. Tap any entry to drop that result back into the display so you can continue from there. Use the Clear button at the top of the History panel to wipe the list; history also survives page reloads but resets if you clear browser storage.

Yes — press √ to take the principal (non-negative) square root of the current display. Press x² to square the display, and 1/x for the reciprocal. These are single-operand functions: they act on the value already shown, not on a pending operation. Taking √ of a negative number surfaces an 'Error' on the screen because the result isn't a real number.

Back deletes only the last character on the display — useful for fixing a single typo without losing the running calculation. AC ('All Clear') wipes everything: the display, the accumulator, the pending operator, and any error state, returning the calculator to a fresh start. Use Back during a long calculation; use AC when you want to start over.

Yes. SamCalculator's basic calculator is fully free, requires no signup, and runs in your browser — desktop, tablet, or phone. There are no ads on the page, no data collection beyond standard hosting logs, and the calculator works offline once the page is cached.

Related Calculators

Need more than four-function arithmetic? Pair the basic calculator with these tools for trig, logs, percentages, and ratio work.