1.1 & 1.2 Decimal Operations Study Guide Practice Activity

​Adding Decimals

• ​Line up decimals.

• ​Annex zeros (fill in empty places)

• ​Add the digits in the same place value position (regroup: carry) if necessary.

• ​Bring the decimal straight down into the sum (answer).

Multiple Choice

Try It! - Find the Sum:

42.46 + 10.44

• 529

• 5,290

• 5.290

• 52.90

​Subtracting Decimals

• ​Line up the decimals places.

• ​Annex (add) zeros has place holders.

• ​Subtract the digits in the same place value position (regroup: borrow) if necessary.

• ​​Bring the decimal straight down into the difference (answer).

Multiple Choice

Try It! - Find the difference:

$$902.3-8.8$$  

• 8,935

• 8.935

• 89.35

• 893.5

​Multiplying Decimals

• Multiply like whole numbers.

• Count the number of decimal places in each factor, then add them together.

• ​Shift the decimal point the total spaces counted from the factors. Place the decimal point in the product (answer).

Multiple Choice

Try It!: Choose the correct product below with the correct decimal placement.

• 3.25944

• 32.5944

• 325.944

• 3259.44

Multiple Choice

Try It! Find the Product:

$$12.5\ \times\ 163.2$$  

• 2.040

• 20.40

• 2,040

• 204.0

Multiple Choice

Try It! Find the Product:

$$5.05\ \times\ 3.1$$  

• 1.5655

• 15.655

• 15,655

• 156.55

Multiple Choice

Which number is the divisor in the problem?

$$1.08\ \div\ 0.027\ =\ 40$$  

• 1.08

• 0.027

• 40

​Dividing Whole Numbers

with Remainders in the Quotient.

• ​​Identify the dividend and divisor in your problem.

• ​Rewrite the division problem using the division house with the dividend under the "house".

• ​Divide normally (think: how many times the divisor can "fit into" the dividend without going over?) ---> Divide, Subtract, Bring Down, Repeat.

• If your remainder is smaller than the divisor and you have nothing else to bring down, write your remainder at the top of the division house next to the quotient.

​Divide Whole Numbers with Decimals in the Quotient.

• ​Identify the dividend and divisor in your problem.

• ​Rewrite the division problem using the division house with the dividend under the "house".

• ​Divide normally (think: how many times the divisor can "fit into" the dividend without going over?) ---> Divide, Subtract, Bring Down, Repeat.

• If your remainder is smaller than the divisor and you have nothing else to bring down, ​annex a zero when you run out of numbers to bring down.

• ​Bring down the number and repeat the division process.

• ​You should have a decimal in your quotient.

Multiple Choice

Try It! Find the Quotient with a decimal:

$$1,248\ \div\ 25$$  

• 4992

• 4.992

• 49.92

• 499.2

Multiple Choice

Try It! Find the Quotient:

$$120.4\ \div\ 602$$  

• 0.02

• 0.20

• 20

• 2

​Dividing Decimals with Decimals in the Dividend

• ​Identify the dividend and divisor in your problem.

• ​Rewrite the division problem using the division house with the dividend under the "house".

• ​Place a decimal point in the quotient by lining it up with the quotient.

• ​Divide normally (think: how many times the divisor can "fit into" the dividend.

​

Multiple Choice

Try It! Find the Quotient:

$$35.75\ \div\ 55$$  

• 65

• 6.5

• 650

• 0.65

​Dividing Decimals with Decimals in the Dividend and Divisor

• Rewrite the problem in the division house.

• ​STEP 1: Move the decimal point in the divisor to the far right of the divisor to make it a whole number.

• STEP 2: ​Move the decimal point the SAME NUMBER of places in the dividend.

• ​STEP 3: Write a decimal point in the quotient above the decimal point in the dividend.

• ​Divide as usual.

Multiple Choice

Try It! Find the Quotient:

$$48.4\ \div\ 0.4$$  

• 1.21

• 0.21

• 121

• 12.10