6.05 Multiply decimals by 2 digit numbers
Are you ready?
Do you remember how to use a standard algorithm to multiply decimal numbers? Let's try this problem to practice.
Find $10.48\times6$10.48×6, giving your answer as a decimal.
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You might notice that sometimes the standard algorithm is called the 'vertical algorithm'. Let's think about why. When we use the standard algorithm, we line our numbers up in 'vertical' place value columns.
Learn
This video looks at how to use the area model to multiply numbers with decimals.
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Question 1
Use the area model to find $46\times4.8$46×4.8.
Fill in the areas of each rectangle.
$4$4 $0.8$0.8 $40$40 $\editable{}$ $\editable{}$ $6$6 $\editable{}$ $\editable{}$ What is the total area of the four rectangles, and therefore the answer to $46\times4.8$46×4.8?
Learn
This video shows how to multiply a decimal number in the hundredths by a $2$2 digit number using the standard algorithm.
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Question 2
We want to find $43\times1.07$43×1.07.
First, choose the most reasonable estimate for $43\times1.07$43×1.07.
$23$23
A$92$92
B$43$43
CFind $43\times1.07$43×1.07, giving your answer as a decimal
When using the standard algorithm to multiply a decimal number by a two digit number we find the product of the first and one of the digits in the second row. After we do this for each digit in the second row, we add all the products together.