Multiplying Decimals I can multiply a decimal fraction by single-digit whole numbers, including using estimation to confirm the placement of the decimal point.

Fluency Practice  Write the multiplication Sentence and say it in unit form.  4 x 2 ones =  4 x 0.2 =  5 x 3 =  5 x 0.3 =  3 x 0.03  3 x 0.23  2 x 0.14  Write the multiplication Sentence and say it in unit form.  4 x 2 ones =  4 x 0.2 =  5 x 3 =  5 x 0.3 =  3 x 0.03  3 x 0.23  2 x 0.14

Word Problem  Patty buys 7 juice boxes a month for lunch. If one juice costs $2.79, how much money does Patty spend on juice each month? Use an area model to solve.  What should you put above the area model?  Patty’s $  Patty buys 7 juice boxes a month for lunch. If one juice costs $2.79, how much money does Patty spend on juice each month? Use an area model to solve.  What should you put above the area model?  Patty’s $

Multiplying Decimals  31 x 4 = 124  3.1 x 4 = 12.4  0.31 x 4 =  How are all three problems alike?  31 x 4 = 124  3.1 x 4 = 12.4  0.31 x 4 =  How are all three problems alike?

Let’s use area models to help us! ? tens + ? ones 4 31 x 4 = ? 3.1 x ones + ? tenth Now, you try it with the last problem: 0.31 x 4 = !!

Multiplying Decimals  5.1 x 6 What is the smallest unit in 5.1?  Multiply 5.1 by 10 to convert it to tenths. How many tenths is the same as 5.1?  What if our multiplication sentence was 51 x 6? Write this vertically and solve.  Is this a reasonable answer for 5.1 x 6?  Where could we place the decimal to make sense?  5.1 x 6 What is the smallest unit in 5.1?  Multiply 5.1 by 10 to convert it to tenths. How many tenths is the same as 5.1?  What if our multiplication sentence was 51 x 6? Write this vertically and solve.  Is this a reasonable answer for 5.1 x 6?  Where could we place the decimal to make sense?

Multiplying Decimals  11.4 x 4 =  What is the smallest unit?  What power of ten must I use to convert 11.4 to tenths?  Write this vertically and solve.  If we estimate, what number is closest to 11.4?  How could this help us get our answer?  11.4 x 4 =  What is the smallest unit?  What power of ten must I use to convert 11.4 to tenths?  Write this vertically and solve.  If we estimate, what number is closest to 11.4?  How could this help us get our answer?

See if you can solve these:  3.12 x 4  3.22 x 5 =  3.42 x 6 =  3.12 x 4  3.22 x 5 =  3.42 x 6 =

We love multiplying  x 4  x 4  x 4  x 4  x 4  x 4

Mathematical Practices  MP 1: Make sense of problems and persevere in solving them.  MP 2: Reason abstractly and quantitatively.  MP 3: Construct viable arguments and critique the reasoning of others.  MP 4: Model with mathematics.  MP 5: Use appropriate tools strategically.  MP 6: Attend to precision.  MP 7: Look for and make use of structure.  MP 8: Look for and express regularity in repeated reasoning.  MP 1: Make sense of problems and persevere in solving them.  MP 2: Reason abstractly and quantitatively.  MP 3: Construct viable arguments and critique the reasoning of others.  MP 4: Model with mathematics.  MP 5: Use appropriate tools strategically.  MP 6: Attend to precision.  MP 7: Look for and make use of structure.  MP 8: Look for and express regularity in repeated reasoning.

What did we learn today?  I can multiply a decimal fraction by single- digit whole numbers, including using estimation to confirm the placement of the decimal point.