Rounding Decimals Review and Multiplying Decimals

___ , ___ ___ ___ ___ ___ ___ ___ Naming Decimals Decimals are read as “and” 5 1 8 2 1 ___ , ___ ___ ___ ___ ___ ___ ___ Thousandths Thousands Ones Hundredths Hundreds Tens Tenths Ten Thousandths Read as 518 and 21 hundredths

Rounding Review Find the number. Circle it. Look next door. 4 or less just ignore. 5 or more add one more. Example: Round 5368 to nearest hundreds. Circle the 3 in the hundreds place. Look next door at the 6. It is 5 or more so add 1 more to the hundreds place. 5368 rounds to 5400

Rounding Review 2.876 31.6999 2.9 31.70 Round to the nearest tenths Round to the nearest hundredths 2.876 31.6999 2.9 31.70

Rounding Review 3.478 22.5972 3.5 22.60 Round to the nearest tenths Round to the nearest hundredths 3.478 22.5972 3.5 22.60

Multiplying Decimals Steps for Multiplying Decimals Step 1: Write the problem vertically. Step 2: Ignore the decimal point(s) and multiply. Step 3: Determine where the decimal point goes in the product. Place the decimal point in the answer by counting how many places the decimal point has moved.

Multiplying Decimals Multiply 3 x 0.14 = 0.42 0.14 3 x 0.14

Multiplying Decimals Multiply 3 x 0.14 0.42 Step 1: Write the problem vertically 0.14 x 3 Step 2: Ignore the decimal points and multiply 4 2 Step 3: Determine where the decimal point goes in the product. 0.42 The decimal moves two places to the left

Multiplying Decimals Multiply 5 x 0.18 0.90 5 x 0.18 0.18 = 1whole

Multiplying Decimals Multiply 5 x 0.18 0.90 4 Step 1: Write the problem vertically 0.18 x 5 Step 2: Ignore the decimal points and multiply 9 Step 3: Determine where the decimal point goes in the product. 0.90 The decimal moves two places to the left

Multiplying Decimals Multiply 0.2 x 0.6 = 0.2 0.6 0.2

Multiplying Decimals Multiply 0.2 x 0.6 = 0.2 x 0.6 0.6 0.2

Multiplying Decimals Multiply 0.2 x 0.6 = 0.2 x 0.6 0.6 0.2 = 0.12

Multiplying Decimals Multiply 0.2 x 0.6 0. 12 Step 1: Write the problem vertically 0.2 x 0.6 Step 2: Ignore the decimal points and multiply 1 2 Step 3: Determine where the decimal point goes in the product. 0. 12 The decimal moves two places to the left

Multiplying Decimals Multiply 0.4 x 0.7 = 0.4 0.7 0.4

Multiplying Decimals Multiply 0.4 x 0.7 = 0.7 0.4 0.4 x 0.7

copyright©amberpasillas2010 Multiplying Decimals Multiply 0.4 x 0.7 = 0.7 0.28 0.4 copyright©amberpasillas2010

Multiplying Decimals Multiply 0.4 x 0.7 0. 28 Step 1: Write the problem vertically 0.4 x 0.7 Step 2: Ignore the decimal points and multiply 2 8 Step 3: Determine where the decimal point goes in the product. 0. 28 The decimal moves two places to the left

. 200 x . 25 1 + 4 5000 Multiplying Decimals Move the decimal two places to the left in your answer. x . 25 1 + 4 . 5000

Multiplying Decimals HOW MANY DECIMAL PLACES? 1) 3.1(0.28) 3.1  0.28 2 decimal places 0.868 1 + 2 = 3 decimal places 2) (0.4)(2.53) 0.4 1 decimal place  2.53 2 decimal places 1.012 1 + 2 = 3 decimal places

Multiplying Decimals 1 2 1 1 0.16 x 30 70 x 1.2 0.0048 x 32 1 4 9 6 4 1) 1 0.16 x 30 2) 70 x 1.2 3) 0.0048 x 32 1 4 1 9 6 4 8 + 7 1 4 4 4 8 8 4 1 5 3 6

3 Evaluate The Power 4 An exponent tells how many times a number is multiplied by itself. 4 3 Exponent Base 4 3 is written as 3 • 3 • 3 • 3 = 81 This exponent is read three to the fourth power.

Evaluate The Power Evaluate (0.2)2 0. 04 This means (0.2)(0.2) 0.2 x 0.2 4 0. 04 The decimal goes moves two places to the left

Calculate Area With Decimals Area = base x height 0.58 in. Multiply 4 x 0.58 4 in. 3 2 The decimal moves two places to the left. 0.58 x 4 Area is square units! 2 3 2 2.32 in2

Review

Multiplying Decimals Multiply 0.4 x 0.14 0.056 #5 Multiply 0.4 x 0.14 1 0.14 x 0.4 Step 1: Write the problem vertically Step 2: Ignore the decimal points and multiply 5 6 Step 3: Determine where the decimal point goes in the product. 0.056 The decimal moves 3 places to the left.

The decimal moves two places to the left. #6 Evaluate (0.5)2 This means (0.5)(0.5) 2 0.5 x 0.5 The decimal moves two places to the left. 2 5 0. 25

Calculate Area With Decimals # 7 Calculate Area With Decimals The Area (A) is the number of square units needed to cover a figure. 0.98 in Area = base x height 2 in. Multiply 2 x 0.98 1 1 The decimal moves two places to the left. 0.98 x 2 1 9 6 Area is square units! 1.96 in2