Multiply decimals by 10, 100, 1000 | Year 5 Mathematics PDF Download

Understanding Multiplying Decimals

Multiplying decimals is a valuable skill that finds applications in various real-life scenarios:

• Converting pounds into pence
• Converting measures, such as kilograms to grams and milliliters to liters
• Converting lengths, for instance, determining the number of meters in centimeters

Understanding Place Value Charts

• Place value charts are helpful tools when multiplying by 10, 100, and 1000, aiding in understanding how digits shift in value:
• An easy trick to remember the number of places digits should move is by noting the zeros in 10, 100, and 1000.
• For example, there are 3 zeros in 1000, so you need to move the digits 3 places to the left to multiply by 1000.
  • x10 - 1 zero means moving 1 place
  • x100 - 2 zeros indicate moving 2 places
  • x1000 - 3 zeros signify moving 3 places

Understanding Multiplying Decimals by 10

Multiplication Concept: When you multiply a decimal by 10, you shift all the digits one place value to the left.
Example: Let's take the example: 4.2 x 10 = 42.
This means that when you multiply 4.2 by 10, the decimal point shifts to the right, making the number 42.
Refer to the image gallery below for a visual representation of how the digits change when you multiply by 10.

• What is 4.2 x 10?
  
• To multiply by 10, shift the digits one place value to the left. Therefore, 4.2 × 10 = 42. Since there are no numbers after the decimal point now, we don't need to include it!

Understanding Multiplying by 100

To multiply a number by 100, you shift all its digits two places to the left. This process essentially increases the number's value by a factor of 100.
3.12 x 100 = 312

• What is 3.12 × 100?
  
• To multiply by 100, shift the digits two places to the left. Thus, 3.12 × 100 = 312.

Understanding Multiplying by 1000

To multiply by 1000, you need to shift the digits three places to the left in the place value chart. This means each digit moves to a position three places higher.
0.04 × 1000 = 40

• What is 0.04 × 1000?
  
• To multiply by 1000, shift the digits three places to the left. Therefore, 0.04 × 1000 = 40.

It's crucial to understand place value when dealing with multiplication by 10, 100, or 1000. The zero in the ones place after multiplication by 1000 signifies that there are no ones in the result.
If we neglect to include this zero, the answer would be incorrect. For instance, 0.04 × 1000 is not 4!
Employing a place value chart can greatly assist in understanding the effects of multiplying by 10, 100, or 1000. It provides a visual representation of how digits shift places with multiplication.