Basic Calculator

Master the four fundamental operations with this calculator:

Chaining Operations: You can perform multiple operations in sequence:

1. Enter 10
2. Press +
3. Enter 5 → Display shows 15
4. Press ×
5. Enter 2 → Display shows 30 (15 × 2)
6. Press = → Final result: 30

Decimal Calculations:

• Enter decimal numbers with the . button
• Example: 3.14 × 2.5 = 7.85
• Results display up to 15 significant digits
• Trailing zeros are automatically removed (2.50 becomes 2.5)

Order of Operations Note: This basic calculator performs operations in the order you enter them (left to right), like a traditional handheld calculator. If you need PEMDAS/BODMAS order (multiplication before addition, etc.), use our Scientific Calculator.

The % button offers two powerful modes:

Mode 1: Convert to Percentage Just enter a number and press %:

• 50 → % → 0.5 (50% as a decimal)
• 15 → % → 0.15 (15% as a decimal)
• 125 → % → 1.25 (125% as a decimal)

Mode 2: Percentage of a Number Use with + or × for common percentage calculations:

Finding a Percentage:

• "What is 20% of 150?"
• Enter: 150 × 20 % =
• Result: 30

Adding a Percentage (Tax, Tips, Markups):

• "Add 8% tax to $45"
• Enter: 45 + 8 % =
• Result: 48.6

Subtracting a Percentage (Discounts):

• "Take 25% off $80"
• Enter: 80 − 25 % =
• Result: 60

Common Percentage Calculations:

Beyond basic math, these buttons enhance your calculating power:

AC (All Clear)

• Clears everything—the display, pending operations, and any stored values
• Use when starting a completely new calculation
• Keyboard shortcut: Escape key

C or CE (Clear Entry)

• Clears only the current entry, keeping previous operations
• Useful when you mistype a number mid-calculation
• Keyboard shortcut: Delete key

± (Plus/Minus Toggle)

• Switches the current number between positive and negative
• Essential for negative numbers: −25 + 15 = −10
• Useful in accounting: toggle between credits and debits
• Works at any point in your calculation

⌫ (Backspace)

• Deletes the last digit entered
• Change 1234 to 123 without starting over
• Keyboard shortcut: Backspace key

Memory Functions (if available):

Power users can calculate faster with keyboard input:

Number Entry:

Operations:

Actions:

Pro Tips:

• Use the numpad for fastest input (enable Num Lock)
• The numpad layout matches physical calculators
• Chain calculations naturally: 5 * 3 Enter + 2 Enter
• Results stay in display for immediate reuse

Speed Example: Calculate (15 × 8) + (23 × 4):

1. Type: 15 * 8 Enter (shows 120)
2. Note result or use M+
3. Type: 23 * 4 Enter (shows 92)
4. Type: + 120 Enter = 212

Every calculation is saved in the history panel below the calculator:

What's Saved:

• The complete expression (e.g., "150 + 25 × 2")
• The final result
• Timestamp (during session)

Using History:

1. Review your work: Scroll through to check calculations
2. Reuse a result: Click any history item to load that result into the display
3. Clear history: Click the "Clear" button to start fresh

History Limitations:

• Last 15-20 calculations are stored
• History clears when you close the browser tab
• No calculations are sent to our servers—everything stays in your browser

Practical Uses:

• Shopping: Track running total while comparing options
• Budgeting: Keep a visible list of expenses
• Homework: Show your work for multi-step problems
• Verification: Double-check a chain of calculations
• Business: Review a series of quotes or estimates

Splitting a Bill: Dinner for 4 people, total $127.50, adding 18% tip:

1. Calculate tip: 127.50 × 18 % = 22.95
2. Add to total: 127.50 + 22.95 = 150.45
3. Split evenly: 150.45 ÷ 4 = 37.61 per person

Price Comparison: Is 3 for $5 or $1.89 each a better deal?

1. Unit price option A: 5 ÷ 3 = 1.67 per item ✓ Better
2. Unit price option B: 1.89 per item

Discount Stacking: $100 item with 20% off, then additional 10% off:

1. First discount: 100 − 20 % = 80
2. Second discount: 80 − 10 % = 72 (Note: This is NOT the same as 30% off, which would be $70)

Simple Interest: $5,000 at 4% annual interest for 1 year:

• 5000 × 4 % = 200 interest earned
• Total after 1 year: 5000 + 200 = 5,200

Measurement Conversion: Convert 5.5 feet to inches (12 inches/foot):

• 5.5 × 12 = 66 inches

How This Calculator Handles Operations:

Left-to-Right Evaluation: This calculator evaluates operations as you enter them:

• 2 + 3 × 4 is calculated as (2 + 3) × 4 = 20
• NOT as 2 + (3 × 4) = 14 (which is mathematical PEMDAS order)

This matches most handheld calculators but differs from mathematical convention. For PEMDAS order, use our Scientific Calculator.

Precision and Rounding:

• Results accurate to 15-16 significant digits
• Very small decimals may show rounding (0.1 + 0.2 might show 0.30000000000000004 due to floating-point math)
• Currency calculations are precise to 2 decimal places in most cases

Division by Zero:

• Dividing by zero displays "Error" or "Infinity"
• Press AC to clear the error and continue

Overflow:

• Very large numbers switch to scientific notation (e.g., 1e+20)
• The calculator handles numbers up to approximately 10^308

Negative Numbers:

• Use ± to make numbers negative
• Example: To calculate -5 + 3: Enter 5, press ±, press +, enter 3, press =
• Result: -2

Advantages Over Phone Calculators:

• Already on your screen—no app switching
• Larger buttons, easier to see results
• Keyboard input for speed
• Visible calculation history
• Works while your phone charges

Advantages Over Physical Calculators:

• Always available with internet access
• No batteries to replace
• No device to lose or break
• History feature not available on most physical calculators
• Free—no purchase required

Advantages Over Computer Calculator Apps:

• No software to install or update
• Works on any device with a browser
• Clean interface without system UI clutter
• Bookmark for instant access

When to Use This Calculator: ✓ Quick arithmetic (tips, totals, splits) ✓ Checking homework problems ✓ Shopping and price comparisons ✓ Basic budgeting and expense tracking ✓ Any simple calculation while browsing

When to Use Scientific Calculator:

• Trigonometry (sin, cos, tan)
• Logarithms and exponentials
• Complex order of operations
• Powers and roots beyond squares

Ensuring Accurate Results:

Double-Check Critical Calculations: For important calculations (finances, measurements), always:

• Perform the calculation twice
• Use an alternative method to verify
• Check that the result is reasonable

Common Input Errors:

Mental Estimation First: Before calculating, estimate the answer:

• 23 × 19 should be "about 400-450"
• If calculator shows 437, that makes sense
• If it shows 43.7 or 4370, you made an error

Sanity Checks:

• Multiplication makes numbers bigger (usually)
• Division makes numbers smaller (usually)
• Adding two positives gives positive result
• The result should be "in the neighborhood" of your estimate

When Precision Matters:

• Financial calculations: round to 2 decimal places
• Measurements: match your measuring tool's precision
• Scientific: maintain significant figures appropriately