Mathematics, Operations (+, -, x, /, etc.)

Grade 3- 5

Objective

Students will learn easy methods of multiplying by 10, 100, and 1000.

Directions

Facts to Know
You can use mental math to multiply by 10. With practice you can probably multiply these problems in your head as quickly as you can use a calculator!
To multiply any number by 10, just add a zero to the number being multiplied.
If you have 10 bags of candy and each bag has 32 candies, you would have 320 candies altogether.
Sample A
32 x 10 = 320
To multiply any number by 100, just add two zeros to the number being multiplied.
If you have 100 hundred bags and each bag has 45 marbles, you would have a total of 4500 marbles.
Sample B
100 x 45 = 4,500
To multiply any number by 1000, just add three zeros to the number being multiplied.
Sample C
1000 x 3569 = 3,569,000
Shortcut to Finding the Product When Factors Are Multiples of 10
When one or more of the numbers being multiplied are multiples of 10, follow these steps:

1. Multiply the parts of each factor that are not zeros.




(2 x 12 = 24)



2. For each of the numbers being multiplied, find the number of zeros from left to right (before reaching a non-zero number) and add the same number of zeros to the product. (In this example, there are 9 zeros. The product should have 9 zeros.)

Resources

• Multiplying by 10, 100, and 1000 activity sheets
• pencils