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TOPIC C: Multiplication of Decimal Numbers
TOPIC C: Multiplication of Decimal Numbers
Dear Family,
Your student is learning to multiply decimal numbers by using methods that are familiar from whole-number multiplication. Students multiply a decimal number by a one-digit whole number; by a multiple of 10, 100, or 1,000; by a two-digit whole number; and by another decimal number. To multiply, students use number lines, place value charts, area models, and vertical form. They relate decimal multiplication to fraction multiplication. Students use their experience multiplying whole numbers to select the most efficient strategy and determine the reasonableness of their answers, with a focus on the placement of the decimal point in the product.
NEW KEY TERMS
inequality
An inequality is a statement that compares two expressions by using > or <. (Lesson 29)
thousandths
Thousandths are a place value unit. 1 one can be decomposed into 1,000 thousandths. (Lesson 1)
FAMILAR TERMS
associative property of multiplication
bundle
exchange
rename
commutative property of multiplication
compare
distributive property
expanded form
exponent
hundredths
long division
power of 10
round tenths
Find a sample of our lessons below to help support MATH TALK at home.
Students also have these in their APPLY workbook.
Lesson 14
Multiply decimal numbers to hundredths by one-digit whole numbers by using different models.
I can think about multiplying a decimal number by a whole number as equal groups or repeated addition. Models such as number lines, place value charts, and area models, which are helpful for whole-number multiplication, can be helpful when multiplying a decimal number by a whole number. I can use unit thinking to help me place the decimal point in the product.
EM2_G5_M4_TC_L14_PracticePartner.pdfEM2_G5_M4_TC_L14_PracticeSolutions.pdfLesson 15
Multiply decimal numbers to hundredths by one-digit whole numbers and multiples of 10, 100, or 1,000 by using different written methods.
Strategies I use to multiply whole numbers can also be helpful when I multiply a decimal number by a one-digit whole number. Thinking about place value units can help me decompose a decimal number and find the unit for the product.
EM2_G5_M4_TC_L15_PracticePartner.pdfEM2_G5_M4_TC_L15_PracticeSolutions.pdfLesson 16
Multiply decimal numbers to hundredths by two-digit whole numbers by using area models and vertical form.
Area models and vertical form can help me find all of the partial products when I multiply a decimal number by a two digit whole number. Unit thinking can help me determine the correct unit for the product.
EM2_G5_M4_TC_L16_PracticePartner.pdfEM2_G5_M4_TC_L16_PracticeSolutions.pdfLesson 17
Multiply decimal numbers to hundredths by two-digit whole numbers by using different methods.
When I multiply decimal numbers by two-digit whole numbers, thinking about each factor helps me choose an efficient multiplication method. I can use vertical form when another method is not helpful.
EM2_G5_M4_TC_L17_PracticePartner.pdfEM2_G5_M4_TC_L17_PracticeSolutions.pdfLesson 18
Relate decimal-number multiplication to fraction multiplication.
To multiply two decimal numbers, I can rename the numbers as fractions. Thinking about the decimal number multiplication as fraction multiplication can help me determine the unit for the product. I can also use place value relationships to shift the digits to find the unit for the product.
EM2_G5_M4_TC_L18_PracticePartner.pdfEM2_G5_M4_TC_L18_PracticeSolutions.pdfLesson 19
Multiply a decimal number by a decimal number.
Vertical form is an efficient way to multiply two decimal numbers. When I multiply a decimal number by a decimal number, I can use several methods to make sure the unit of the product is reasonable.
EM2_G5_M4_TC_L19_PracticePartner.pdfEM2_G5_M4_TC_L19_PracticeSolutions.pdfReport abuse