Calculation methodology

Every NumoCrunch answer comes from a plain arithmetic formula evaluated in your browser. There is no server round-trip, no stored data and no hidden adjustment.

Formulas we use

• Tip CalculatorBill × Tip %
• Decrease by PercentageX × (1 − Y ÷ 100)
• Increase by PercentageX × (1 + Y ÷ 100)
• Test Score CalculatorCorrect ÷ Total × 100
• Mixed Fraction to Percent(A × C + B) ÷ C × 100
• What Percent Is X of YX ÷ Y × 100
• What Is X% of YX × Y ÷ 100
• Reverse Percentage — X Is Y% of WhatX ÷ (Y ÷ 100)
• Percent Change(Y − X) ÷ X × 100

Rounding

Results are calculated at full floating-point precision and only rounded for display — currency to 2 decimal places, percentages to 2 decimal places, and other values to at most 4. Intermediate steps shown in the explanation use the same rounding, so a hand-checked answer may differ in the final digit.

Grading scale

Letter grades use the standard US scale: A ≥ 93, A− ≥ 90, B ≥ 83, C ≥ 73, D ≥ 63, F below 60, with plus grades at 97, 87, 77 and 67. Schools vary — always check your syllabus.

Privacy

The numbers you type stay on your device. Saved test scores are stored only in your browser's local storage and never transmitted. See our privacy policy.