**Middle School Number Sense Lesson 16: Multiplying Two 2-digit Numbers whose Units Digits Are the Same, and whose Tens Digits Add up to 10**

This concept is actually much shorter than the title suggests. It appeared

**11 times**this year--as early as question 13 and as late as question 59, but normally around

**question # 17**. Before trying to solve these problems, make sure the following conditions are met:

- Both numbers are 2-digit integers.
- The units digits are the same.
- The tens digits add up to ten.

**Number Dojo Level: 84**

**How to Solve:**

- Square the units digit and write this down as the last 2 digits of your answer. (Write 01 instead of 1, 04 instead of 4, etc.).
- Multiply the two tens' digits and add one of the units' digits. Write this in front of what you wrote down in step 1. You're done!

**Example 1: 63 x 43**

- Square the 3 to get 9, and write it down as 2 digits:
**09**. - Multiply 6 by 4 to get 24, and add the 3 to get
**27**. Write this in front to get**2709**.

**Example 2: 18 x 98**

- Square the 8 to get
**64**, and write this down. - Multiply 1 by 9 to get 9, and add the 8 to get
**17**. Write this in front to get**1764**.

**Example 3: 72 x 32**

- Square the 2 to get 4, and write it down as 2 digits:
**04**. - Multiply 7 by 3 to get 21, and add the 2 to get
**23**. Write this in front to get**2304**.

**Example 4: 2.9 x 8.9**

- Don't let the decimals fool you--you can still solve this problem the same way. Square the 9 to get
**81**, and write this down. - Multiply 2 by 8 to get 16, and add the 9 to get
**25**. Write this in front, and remember to use 2 decimal places to get**25.81**.

**Example 5: 58 x 58**

- Square 8 to get
**64**, and write this down. - 5 x 5 + 8 = 25 + 8 =
**33**. Write this down in front to get**3364**.

**Here's a free worksheet to help you practice MultUs,10+10:**

multus10_10.pdf |

**And a video.**

Up Next for Middle School: SquareEnd5

Up Next for Middle School: SquareEnd5