Warm Up Problem Natalie bought 12 pens for $0.59 each. She paid with a $10 bill. How much change will she receive?

Multiply Decimals by Decimals Lesson 3-4

Objectives I can multiply decimal numbers by decimal numbers. I can use estimation to justify my answer.

Example 1 Find 3.6 x 0.05. 1) Count the number of digits to the right of the decimal point in BOTH factors. 3 2) Multiply without the decimals: 36 x 5 180 3) Add back 3 decimal places to the right. 0.180 or 0.18

Example 2 Find 0.112 x 7.2. Count the total number of digits to the right of the decimal. 4 Multiply: 112 x 72 224 + 7840 8064 Add the decimal back with 4 places to the right: 0.8064

Got It? 1) 5.7 x 2.8 2) 0.014 x 3.7

Example 3 Find 1.4 x 0.067 1) Count up the numbers to the right of the decimal. 4 2) Multiply: 67 X 14 268 + 670 938 3) Add the decimal back. Annex a zero, if necessary. 0.0938

Example 4 Find 0.45 x 0.053. 1) Count up the digits to the right. 5 2) Multiply: 53 x 45 265 + 2120 2385 3) Add the decimal back. Annex zeros, if necessary. 0.02385

Got It? 3) 0.04 x 0.32 4) 0.26 x 0.205

Homework Hint #13 What do you notice about the decimal point when multiplying? X 3 0.3 0.03 0.003 4 12 1.2 0.12 0.4 0.012 0.0012 0.04 0.004