A percentage represents a fraction in terms of 100. The basic formula is:

Percentage = (Value ÷ Total) × 100

For example:

• If you got 75 marks out of 100, your percentage is (75 ÷ 100) × 100 = 75%
• If you want to find 15% of 200, calculate (15 × 200) ÷ 100 = 30

The calculator offers three modes:

1. Simple Mode: Calculate what percentage one number is of another
2. Marks Mode: Convert obtained marks to percentage and view grade
3. Change Mode: Calculate percentage increase or decrease between two values

Select the appropriate mode button at the top of the calculator for your calculation.

To calculate percentage change:

1. Select the "Change" mode
2. Enter the original value
3. Enter the new value
4. The calculator will show:
• Percentage change value
• Whether it's an increase or decrease
• Visual indicator (↑ or ↓)

Percentage Change = [(New Value - Original Value) ÷ Original Value] × 100

The grading scale used is:

• 90-100%: A (Excellent)
• 80-89%: B (Very Good)
• 70-79%: C (Good)
• 60-69%: D (Pass)
• Below 60%: F (Fail)

The progress bar provides a visual representation of your performance within these ranges.

To convert decimals to percentages:

1. Multiply the decimal by 100
2. Add the % symbol

Common conversions:

• 0.1 = 10%
• 0.25 = 25%
• 0.5 = 50%
• 0.75 = 75%
• 1.0 = 100%

The calculator handles these conversions automatically.

The calculator shows two decimal places because:

• It provides more precise results
• Helps in comparing close percentages
• Useful for academic and financial calculations

For example, 83.33% is more precise than just 83%.

You can round to whole numbers if needed for your specific use case.

Yes, the calculator can handle negative numbers:

• In Simple mode: for calculating percentages of negative values
• In Change mode: to show decreases in value

Example scenarios:

• Temperature changes (below zero)
• Financial losses
• Negative growth rates

The calculator will show appropriate indicators for negative results.