Multiplication with large numbers can be error-prone, both because of the large numbers involved and the alternating addition and multiplication operations performed. A partial product multiplication streamlines the procedure: you perform all the multiplication steps first, then add the partial results to get the final answer. It is based on an understanding of place value and makes use of the distributive property.
Instructions
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1
Break up the number into its component parts. Let us take for example 453*25. The multiplicand can be written as:
400
50
3
And the multiplier is
20
5
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2
Use the distributive property to multiply.
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3
Multiply:
400*20 = 8000
50*20 = 1000
3*20 = 60
400*5 = 2000
50*5 = 250
3*5 = 15
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4
Add:
8000+1000+60+2000+250+15 = 11325.
When working the problem on paper put placeholders at the start of the following lines so the digits line up accurately.