Porcentage Calculator

Percentage Calculator

Percentages are a fundamental part of mathematics and are used extensively in everyday life, from calculating discounts and tips to understanding statistics and financial growth. A percentage represents a fraction of 100, denoted by the symbol "%". For example, 50% means 50 out of 100, or 0.5 as a decimal.

This calculator helps you perform three common percentage-related calculations:

1. What is X% of Y? Find a specific percentage of a given number.
2. Percentage Change: Calculate the percentage increase or decrease between two numbers.
3. Number from Percentage: Determine the whole number when you know a part of it and its percentage.

1. What is X% of Y?

Use this to find a portion of a number. For example, what is 20% of 150?

2. Percentage Change

Calculate the percentage increase or decrease between two numbers. For example, from 100 to 120 is a 20% increase.

3. Number from Percentage

Find the whole number when you know a part and its percentage. For example, if 30 is 15% of a number, what is that number?

Understanding Percentages

The word "percent" comes from the Latin phrase "per centum," meaning "by the hundred." It's a way to express a number as a fraction of 100. For instance, if you score 85 out of 100 on a test, your score is 85%. If you score 17 out of 20, you can convert this to a percentage by finding an equivalent fraction with a denominator of 100: (17/20) * 100 = 85%.

Percentages are dimensionless numbers, meaning they don't have units like meters or kilograms. They are ratios that help us compare quantities proportionally.

Practical Applications:

• Retail: Discounts (e.g., "25% off"), sales tax.
• Finance: Interest rates, stock market changes, inflation rates.
• Statistics: Survey results, population growth rates.
• Health: Body fat percentage, daily nutritional values.
• Education: Test scores, attendance rates.

function calculatePercentageOfNumber() { var percentValue = parseFloat(document.getElementById('percentValue').value); var baseNumber = parseFloat(document.getElementById('baseNumber').value); var resultDiv = document.getElementById('resultPercentageOfNumber'); if (isNaN(percentValue) || isNaN(baseNumber)) { resultDiv.innerHTML = "Please enter valid numbers for both fields."; return; } var result = (percentValue / 100) * baseNumber; resultDiv.innerHTML = percentValue + "% of " + baseNumber + " is: " + result.toFixed(2); } function calculatePercentageChange() { var originalValue = parseFloat(document.getElementById('originalValue').value); var newValue = parseFloat(document.getElementById('newValue').value); var resultDiv = document.getElementById('resultPercentageChange'); if (isNaN(originalValue) || isNaN(newValue)) { resultDiv.innerHTML = "Please enter valid numbers for both fields."; return; } if (originalValue === 0) { resultDiv.innerHTML = "Original Value cannot be zero for percentage change calculation."; return; } var change = newValue – originalValue; var percentageChange = (change / originalValue) * 100; if (percentageChange > 0) { resultDiv.innerHTML = "Percentage Increase: " + percentageChange.toFixed(2) + "%"; } else if (percentageChange < 0) { resultDiv.innerHTML = "Percentage Decrease: " + Math.abs(percentageChange).toFixed(2) + "%"; } else { resultDiv.innerHTML = "No Change (0%)"; } } function calculateNumberFromPercentage() { var partValue = parseFloat(document.getElementById('partValue').value); var percentageOfTotal = parseFloat(document.getElementById('percentageOfTotal').value); var resultDiv = document.getElementById('resultNumberFromPercentage'); if (isNaN(partValue) || isNaN(percentageOfTotal)) { resultDiv.innerHTML = "Please enter valid numbers for both fields."; return; } if (percentageOfTotal === 0) { resultDiv.innerHTML = "Percentage cannot be zero."; return; } var totalNumber = (partValue / percentageOfTotal) * 100; resultDiv.innerHTML = partValue + " is " + percentageOfTotal + "% of: " + totalNumber.toFixed(2); }