What is a percent? Can you give an example?

A percent is a ratio out of 100. 34% is 34 out of 100.

How can you write a percent as a fraction and as a decimal?

To write a percent as a fraction, write the number as the numerator over denominator 100, and then simplify. For example, 34% is [ggfrac]34/100[/ggfrac] or [ggfrac]17/50[/ggfrac]. To write a percent as a decimal, divide the number by 100. 34% = 0.34.

How can you calculate the part of a whole, given a percent? Give an example.

I change the percent to a decimal then multiply by the whole. 34% of 50 is 0.34 × 50 = 14.

How can you calculate a percent given the part and the whole?

percent = [ggfrac]part/whole[/ggfrac]. First, write a ratio of [ggfrac]part/whole[/ggfrac], and then divide to write it as a decimal. Multiply by 100 to write the value as a percent.

How can you calculate the whole if you know the part and the percent?

percent = [ggfrac]part/whole[/ggfrac], so whole = [ggfrac]part/percent[/ggfrac]. Write the percent as decimal, and then divide the part by the decimal to get the value of the whole.

How can you tell if the problem you want to solve is a percent increase or percent decrease problem?

I can look for keywords such as "more" or context-based words like “tax” or ”tip” to identify when the value is increasing. I can look for keywords such as "less" or context-based words like "discount" or "sale" to identify when the value is decreasing.

Given a percent increase, how can you calculate the total amount?

First, I calculate the part that represents the percent increase by multiplying the percent by the initial amount. Then, I add that amount to the original amount.

Given a percent decrease, how can you calculate the total amount?

First, I calculate the part that represents the percent decrease by multiplying the percent by the initial amount. Then, I subtract that amount from the original amount.

Given an original amount and an increased amount, how can you calculate the percent increase?

First I subtract to find the difference between the original and increased amounts. Then I divide by the original amount to find the percent change as a decimal. Multiply by 100 to write it as a percent.

Given an original amount and a decreased amount, how can you calculate the percent decrease?

It is the same process as for an increased amount. First I subtract to find the difference between the original and decreased amounts. Then I divide by the original amount to find the percent change as a decimal. Multiply by 100 to write it as a percent.

Percent Change

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Percent Change

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What you will learn from this videoWhat you will learn

We’ll learn how to to solve multi-step percent problems.
We’ll also learn how to calculate percent increase and percent decrease.
And we'll see how this knowledge can help us buy items on sale, learn about different schools, and see how much our things are worth!

Discussion Questions
- Before Video
  What is a percent? Can you give an example?ANSWER
  - A percent is a ratio out of 100. 34% is 34 out of 100.
  How can you write a percent as a fraction and as a decimal?ANSWER
  - To write a percent as a fraction, write the number as the numerator over denominator 100, and then simplify. For example, 34% is [ggfrac]34/100[/ggfrac] or [ggfrac]17/50[/ggfrac]. To write a percent as a decimal, divide the number by 100. 34% = 0.34.
  How can you calculate the part of a whole, given a percent? Give an example.ANSWER
  - I change the percent to a decimal then multiply by the whole. 34% of 50 is 0.34 × 50 = 14.
  How can you calculate a percent given the part and the whole?ANSWER
  - percent = [ggfrac]part/whole[/ggfrac]. First, write a ratio of [ggfrac]part/whole[/ggfrac], and then divide to write it as a decimal. Multiply by 100 to write the value as a percent.
  How can you calculate the whole if you know the part and the percent?ANSWER
  - percent = [ggfrac]part/whole[/ggfrac], so whole = [ggfrac]part/percent[/ggfrac]. Write the percent as decimal, and then divide the part by the decimal to get the value of the whole.
- After Video
  How can you tell if the problem you want to solve is a percent increase or percent decrease problem?ANSWER
  - I can look for keywords such as "more" or context-based words like “tax” or ”tip” to identify when the value is increasing. I can look for keywords such as "less" or context-based words like "discount" or "sale" to identify when the value is decreasing.
  Given a percent increase, how can you calculate the total amount?ANSWER
  - First, I calculate the part that represents the percent increase by multiplying the percent by the initial amount. Then, I add that amount to the original amount.
  Given a percent decrease, how can you calculate the total amount?ANSWER
  - First, I calculate the part that represents the percent decrease by multiplying the percent by the initial amount. Then, I subtract that amount from the original amount.
  Given an original amount and an increased amount, how can you calculate the percent increase?ANSWER
  - First I subtract to find the difference between the original and increased amounts. Then I divide by the original amount to find the percent change as a decimal. Multiply by 100 to write it as a percent.
  Given an original amount and a decreased amount, how can you calculate the percent decrease?ANSWER
  - It is the same process as for an increased amount. First I subtract to find the difference between the original and decreased amounts. Then I divide by the original amount to find the percent change as a decimal. Multiply by 100 to write it as a percent.
Vocabulary
- Ratio DEFINE
- Percent DEFINE
- Two-step problem DEFINE
- Percent increase DEFINE
- Percent decrease DEFINE
- Pie chart DEFINE
Reading Material
Practice Word Problems
Practice Number Problems
Lesson Plan
Teacher Guide
Assessment
Online Quiz Game Quiz PDF Exit Ticket