Basic Calculator | PEMDAS, Memory & Shortcuts

Q: How do I use the memory functions (MC, MR, MS, M+, M-)?

MC clears memory to zero. MR puts the stored value on the display. MS replaces memory with what’s on screen. M+ and M− add or subtract the display from memory. The M badge shows when memory isn’t zero. Handy for one number you reuse (a tax rate, a running total) while you keep calculating on the main display.

Q: Does the calculator follow order of operations?

Yes for × and ÷ before + and −. 3 + 5 × 2 = 13, because 5 × 2 runs first. Many cheap desk calculators go left-to-right and show 16. There are no parentheses keys on this pad, so you can’t type (3 + 5) × 2 here; use the Scientific Calculator for grouped expressions.

Q: How do I view my calculation history?

Click Show History above the display. You’ll see the last 10 expressions and results. History lives in the tab until you refresh the page or clear it; it isn’t saved to the server.

Q: Can I use keyboard shortcuts?

Yes: digits and + − * /, Enter or = to calculate, Backspace to delete a digit, Esc or C to clear all, % for percentage, M for memory recall, Shift+M for memory store. MC, M+, and M− are on-screen only.

Q: How does the calculator handle very large or small numbers?

Values with absolute size ≥ 10¹⁵ or between 0 and 10⁻⁶ switch to scientific notation (six significant figures). Ordinary results use comma thousands separators (1,000,000). That keeps long grocery totals readable without losing precision on tiny or huge values.

Q: Why does 0.1 + 0.2 look right here?

The math uses decimal arithmetic, not the usual JavaScript floating-point numbers, so 0.1 + 0.2 displays as 0.3 instead of 0.30000000000000004. Handy for money and homework checks where float noise is annoying.

3 + 5 × 2 = 13

Type the expression in one go and press equals: multiplication runs before addition, so you get 13, not 16. Memory, a 10-line history tape, keyboard entry, and high-precision decimal math sit on the same pad as √, x², and 1/x for quick checks.

Four things that change how you use it

Precedence beats left-to-right

Chain 10 − 4 ÷ 2 and you get 8 (divide first), not 3. That matches algebra class, not every four-function desk calculator. If you need parentheses around a sum, this pad has no ( ) keys; group the steps manually or open the Scientific Calculator.

Memory is one slot; history is a scrollback

MS/MR/M+/M− hold a single running value (example: 10 + 5 → M+, then 20 + 3 → M+, MR shows 38). History lists the last 10 completed lines so you can re-read an expression. Use memory when one number keeps coming back; use history when you want the full trail.

The % key depends on what’s already on screen

With 100 on the stack and × then 15 on the display, % gives 15 (15% of 100). With + instead of ×, % adds 15% of the left operand (110). With nothing pending, % divides the display by 100 (15 → 0.15). It does not multiply by 100 to spell out “15%”.

Float quirks are deliberately avoided

Penny-style sums like 0.1 + 0.2 land on 0.3 instead of a long float tail. Very big or tiny magnitudes flip to scientific notation so the display doesn’t overflow with digits.

Basic calculator: PEMDAS-style precedence, memory, and history

3 + 5 × 2 = 13 here (not 16). 0.1 + 0.2 shows 0.3, memory holds a running total, and the tape keeps your last 10 lines in the browser.

What this calculator does

Everyday + − × ÷ with multiplication and division evaluated before addition and subtraction. One memory register (MC, MR, MS, M+, M−), a 10-entry history tape, comma formatting, automatic scientific notation past 10¹⁵ or below 10⁻⁶, and extra keys for %, √, x², 1/x, and sign flip. Full keyboard support for digits, operators, equals, clear, backspace, %, and memory store/recall.

Outputs:

Formatted result on the display; optional history lines showing expression → result.
Limits:

No parentheses or exponent keys on this pad (precedence is ×/÷ then +/− only). History is in-memory for the session, not synced across devices. MC/M+/M− aren’t mapped to keys. Needs a loaded page; it isn’t a native offline app unless your browser already cached the site.

The math

When you press equals, the tool tokenizes the expression, applies ×, ÷, and % modulo left to right among themselves, then finishes with + and −. Unary minus on a leading negative is supported; nested parentheses are not, because there’s no way to enter them.

Precedence examples:

3 + 5 × 2 → 13. 10 − 4 ÷ 2 → 8. 2 × 3 + 4 × 5 → 26 (both products, then the sum).
Decimal arithmetic:

0.1 + 0.2 → 0.3 on screen. Division by zero shows Error.
Percentage:

100 × 15 then % → 15. 100 + 10 then % → 110 (adds 10% of 100). Plain 15 then % → 0.15 (divide display by 100).
Memory worked example:

Calculate 10 + 5, M+, calculate 20 + 3, M+, MR → 38.
Display formatting:

Commas on normal-sized integers and decimals; scientific notation at |x| ≥ 10¹⁵ or 0 < |x| < 10⁻⁶.

Using the calculator

Mouse or keyboard both work. The expression preview under the header helps catch typos before you hit equals.

Keyboard:

0–9, + − * /, ., Enter/=, Backspace, Esc/C clear, %, M recall, Shift+M store.
Memory buttons:

MC clear, MR recall, MS replace, M+ / M− accumulate. M badge when memory ≠ 0.
History:

Show History toggles the tape; newest lines on top; max 10 entries.
Extra keys:

√, x², 1/x, ± act on the current display value (not a chained expression).
Accessibility:

Buttons and the display carry aria-labels; keyboard paths avoid requiring a pointer. We don’t claim a formal WCAG audit here.
Privacy:

Calculations stay in your browser; nothing is posted to a server.

FAQ

How do I use the memory functions (MC, MR, MS, M+, M-)?

MC clears memory to zero. MR puts the stored value on the display. MS replaces memory with what’s on screen. M+ and M− add or subtract the display from memory. The M badge shows when memory isn’t zero. Handy for one number you reuse (a tax rate, a running total) while you keep calculating on the main display.

Does the calculator follow order of operations?

Yes for × and ÷ before + and −. 3 + 5 × 2 = 13, because 5 × 2 runs first. Many cheap desk calculators go left-to-right and show 16. There are no parentheses keys on this pad, so you can’t type (3 + 5) × 2 here; use the Scientific Calculator for grouped expressions.

How do I view my calculation history?

Click Show History above the display. You’ll see the last 10 expressions and results. History lives in the tab until you refresh the page or clear it; it isn’t saved to the server.

Can I use keyboard shortcuts?

Yes: digits and + − * /, Enter or = to calculate, Backspace to delete a digit, Esc or C to clear all, % for percentage, M for memory recall, Shift+M for memory store. MC, M+, and M− are on-screen only.

How does the calculator handle very large or small numbers?

Values with absolute size ≥ 10¹⁵ or between 0 and 10⁻⁶ switch to scientific notation (six significant figures). Ordinary results use comma thousands separators (1,000,000). That keeps long grocery totals readable without losing precision on tiny or huge values.

Why does 0.1 + 0.2 look right here?

The math uses decimal arithmetic, not the usual JavaScript floating-point numbers, so 0.1 + 0.2 displays as 0.3 instead of 0.30000000000000004. Handy for money and homework checks where float noise is annoying.

Mathematical Reference Note

Calculation Logic: This tool uses standard mathematical algorithms. While we strive for accuracy, errors in logic or user input can result in incorrect data.

Verification: Results should be cross-checked if used for important academic, professional, or personal calculations.

Standard Terms: This tool is provided free of charge and as-is. CalcRegistry provides no warranty regarding the accuracy or fitness of these results for your specific needs.