Practice Multiplying Decimals by a 2-Digit Number

31.7 x  1 decimal place 1 decimal place Evaluate:31.7 x 13

8.20 x  2 decimal places 2 decimal places Evaluate:34 x 8.20

42.3 x  1 decimal place 1 decimal place Evaluate:17 x

2.132 x  3 decimal places 3 decimal places Evaluate:14 x

7.35 x  2 decimal places 2 decimal places Evaluate:7.35 x

57.6 x  1 decimal place 1 decimal place Evaluate:14 x

Directions: Quietly, put your markers, boards, and erasers back into the bin. We will use them later. Open up to your table of contents.

Multiplying with Decimals

Multiplying Whole Numbers 25 x 12

Multiply: 25 x Multiply the ones Multiply the tens Add the products 300

Hmmm but what if 12 was 1.2? What do you notice about the change of 12 to 1.2?? If we compared the answer of 25 x 12 and the answer of 25 x 1.2, which answer do you think would be bigger and why?

Multiply: x 12 x

Multiply: 25  no decimal place x 1.2  1 decimal place decimal place

Multiply: A 52  no decimal place x.31  2 decimal places decimal places

Multiply: B 1.4  1 decimal place x 5.6  1 decimal place decimal places

Place the decimal point in the product A 23.5 x

Place the decimal point in the product B 6.65 x

Place the decimal point in the product C 54.1 x

Place the decimal point in the product D 1.89 x

How many times do you move the decimal??? A) 4 x.25 Two Decimal Places B) 9.8 x 7 One Decimal Place C) 25.3 x 21.5 Two Decimal Places D) 87.3 x 5.66 Three Decimal Places E).289 x 4.2 Four Decimal Places

Moving the Decimal the CORRECT NUMBER of Places One Decimal Place Two Decimal Places Three Decimal Places Four Decimal Places

Let’s Begin… 2. 6 X X X X X X X X X X 3.2

. 4 6 X X X X X X X X X X 1 2 One Decimal PlaceTwo Decimal Places Three Decimal Places Four Decimal Places

Your turn to try it out!

Multiplying with Decimals

Place the decimal point in the product A 42.7 x

Place the decimal point in the product B 4.23 x

Place the decimal point in the product C 1.23 x

Independent Practice

Multiply: 34 x  no decimal place  1 decimal place 1 decimal place

Multiply: 52 x  no decimal place  2 decimal places 2 decimal places

Multiply: 7.3 x  1 decimal place 2 decimal places

Multiply: 9.2 x  1 decimal place  2 decimal places 3 decimal places

Multiply:.37 x  2 decimal places 4 decimal places

Wrap -Up Why would the answer to … 250 And 250 X 3.4x 34 be different even though they have the same numbers?

Make it easy with…. ESTIMATION!

iPod Nano- 4 th generation $89.99 What if you and your 2 friends wanted to buy the iPod Nano, about how much would it cost? $89.99 x 3 $90 x 3 Estimate: $270

Kodak Camera SALE $77.75 What if you wanted to buy the last 2 Kodak Cameras that were left on the shelf, about how much would it cost? $77.75 x 2 $80 x 2 Estimate:$160

Gas Prices One gallon of Unleaded gas costs $3.61 The car you ride in needs 9.5 gallons of gas to be at a FULL TANK. About how much money would be spent to fill up the car’s tank? 9.5 x $ x $3 Cost would be about $30

Gas Prices 1 gallon of Unleaded gas costs $3.61 What if you needed 15.6 gallons for a FULL TANK? About how much money would it take? 15.6 x $ x $3 Cost would be about $60