Assessment and Learning in Knowledge Spaces (ALEKS) Basic Math Placement Practice Test

What is the process for multiplying with decimals, given the example 9 x 0.6?

1. Multiply as whole numbers, then add a decimal

2. Multiply as whole numbers, then divide by 10

3. Multiply by 6, then subtract 1

4. Multiply and keep the decimal as is

The correct answer is: Multiply as whole numbers, then divide by 10

To multiply with decimals, the correct process involves multiplying the numbers as if they were whole numbers and then adjusting for the decimal places. In the example of \(9 \times 0.6\), you first ignore the decimal and multiply 9 by 6, which gives you 54. Next, you need to consider the decimal in 0.6; since there is one decimal place in 0.6, you place the decimal in your product (54) accordingly, which results in 5.4. This process reflects the essence of option B, where you multiply as whole numbers and then divide by a power of 10, in this case by 10. Also, the counting of the decimal places effectively means you shift the result left, confirming that this option accurately represents the correct method for handling decimal multiplication. Understanding this process helps ensure that students can correctly multiply decimals not just in simple cases, but in more complex calculations as well.