Calculating Numbers Through Percentages |
Quick Reminder |
Last week we learned how to find the percentage based off two whole numbers. Today, we are going to find out a whole number using a percentage and a different whole number. To do this, we need to do the opposite.
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To find the percentage you had to:
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Example - Tip
You have just eaten at a restaurant, you had spaghetti and meatballs. The menu said it was 18$. At the end of the meal, you are asked to add 15% tip for the waiter.
How much is the tip?
Example - Tip part 2You really liked the spaghetti, so you invite your friends. They all have the meal. Your friend decides to pay for the entire meal (nice!). It comes to $72. Your friend also decides to tip 18%, as the waiter was very nice. How much is he paying total?
Because you are trying to find out the total you can use a shortcut in step 2. Multiply the original cost of the meal by the decimal + 1 whole number.
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Example - Discounts
You are at the store, and you see a shirt you really like, and better yet, it says 15% off! But the discount price isn't listed... how much are you saving if the shirt was originally $30?
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Formula
- Turn the percent into its decimal form
- Multiply the decimal form percent with the other whole number.
- If it is tip or additive, add the amount to the original
- If it is discount or subtractive, remove that amount from the original
Questions
- What is the discount on a $45 shirt if it is 20% off?
- If the tip amount is 17% how much am I paying on a meal that cost $32?
- 60% off sale! Everything must go! I buy $580 worth of things. How much did I save?
- I bought shoes today, they're $60. But with taxes it will go up. Tax is 14%, how much more am I spending?
- Which shirt is the least expensive buy? Shirt A that is 35% off listed at $95 or shirt B that is 10% off listed at $70