### Friendly numbers are a special type of number that have a unique connection with other numbers. To understand this relationship, we will add up all of the factors of a number and then we look at the index of a number and compare it to the index of another number. Check it out in this mini spark.

### Spark your math thinking!

1. Set up your math mini spark recording page: #102: Friendly Numbers

2. Review factors. Read this paragraph and when you are done write the factors of the number 40 on your recording sheet.

**Factors are numbers you multiply together to get another number. A factor of a number divides the number evenly, with no remainder. What are all the factors of the number 8? 1 2 4 8 What are all the factors of the number 24? 1 2 3 4 6 8 12 24**

3. Scroll down to the bottom of this page to see if you have the correct numbers for step 2. If you do put a star on your page. If you do not, add the correct numbers.

4. Look over these 6 questions before your start watching the video.

- Stop the video at 2:57. In two sentences, describe how 12 and 234 and are friendly numbers.
- How many perfect numbers are there. How has this number changed since 2011?
- What is is called if you don’t have a friend? Name a few of these types of numbers.
- Pause the video at 8:40 and write down all of the friendly numbers on his chart.
- What are the yellow numbers?
- What is 10’s index?

5. Share your math mini spark recording page with your teacher/EY coordinator

Answers for step 3

Factors of 40 are 1, 2, 4, 5, 8, 10, 20, 40