What this calculates: Use this when you know the percentage and want to find the amount.

Example 1: A loan charges 3% interest on $10,000. The interest is $300.
Example 2: A store gives a 10% discount on a $6,000 order. You save $600.
Example 3: A 15% fee applies to goods worth $25,000. The fee is $3,750.

What this calculates: Use this to find what percentage one amount is of another.

Example 1: You earn $30 from a $1,000 investment. That return is 3%.
Example 2: A product costs $165 to make and sells for $380. The cost is about 43.42% of the selling price.

What this calculates: Use this when you know an amount and the percentage it represents.

Example 1: If 500 is 10% of a number, the original value is 5,000.
Example 2: A $30,000 return equals 3% of an investment. The original investment was $1,000,000.

What this calculates: Compare a starting value with a new value to find the percentage increase or decrease.

Example 1: Sales rise from 100 to 200. That is a 100% increase.
Example 2: Sales fall from 500 to 250. That is a 50% decrease.

What this calculates: Find profit as a percentage of the original cost.

Example 1: Buy an item for $200 and sell it for $300. The profit is 50%.
Example 2: Buy stock for $500 and sell it for $750. The profit is 50%.

What this calculates: Find a loss as a percentage of the original cost.

Example 1: Buy a phone for $20,000 and sell it for $15,000. The loss is 25%.
Example 2: Buy an item for $1,000 and sell it for $500. The loss is 50%.