Standard 1Use various strategies to and operations to

solve problems involving real numbers.

Decimal numbers are known as rational numbers. To understand decimals it is important to understand place value. (Poster)

Rational Numbers

Round the number 568.4587 to the nearest:

A. Tenth:B. Hundredth: C. Thousandth:

Rounding Decimals

Round the following decimals to the nearest tenth.

1. 45.58 5. 4.5432. 17.041 6. 91.3853. 5.284 7. 25.4834. 0.618 8. 0.349

Rounding Decimals

Round to the nearest hundredth.

1. 10.049 5. 6.3542. 0.753 6. 5.7293. 6.432 7. 13.0064. 32.896 8. 31.456

Rounding Decimals

Order the following decimals from least to greatest.

1. 0.055, 0.05, 0.59, 0.052. 0.7, 0.732, 0.74, 0.723. 0.19, 0.09, 0.9, 0.1

Ordering Decimals

When adding decimals, first arrange the numbers in columns with the decimal points under each other.

Ex. 0.9 + 2.5 + 63.17 =

Adding Decimals

Add. Be sure to write the decimal point in your answer.

1. 5.3 + 6.02 + 0.73

2. $3.75 + $18.90

3. 1.25 + 4.1 + 10.007

Adding Decimals

When you subtract decimals, arrange the numbers in columns with the decimal points under each other.

Example: 5.25 – 4.7

Subtracting Decimals

Subtract. Be sure to write the decimal point in your answer.

1. 23.657 – 9.832. $40.99 – $9.993. 15.789 – 6.324. 102.5 – 1.079

Subtracting Decimals

Set up the problem as if you were multiplying whole numbers.

Multiply as if you were multiplying whole numbers.

Count how many numbers are after the decimal points in the problem.

Example: 15.2 x 3.5 =

Multiplication of Decimals

Multiply.1. 9.54 x 5.32. 5.72 x 6.33. 4.8 x 3.24. 5.003 x 0.009

Multiplication of Decimals

Copy the problem as you would for whole numbers. Copy the decimal point directly above in the place for the answer.

Example: 52.26 ÷ 6 =

Division of Decimals by Whole Numbers

Divide.

1. 42.75 ÷ 3

2. 74.16 ÷ 6

3. 152.25 ÷ 21

Division of Decimals by Whole Numbers

Copy the problem as you would for whole numbers.

You cannot divide by a decimal number. What you do to the outside – you must do to

the inside.

Example: 374.5 ÷ 0.07

Division of Decimals by Decimals

Divide.

1. 0.676 ÷ 0.013

2. 70.32 ÷ 0.08

3. $54.60 ÷ 0.84

Division of Decimals by Decimals

Write the following fractions as decimals.

A. C.

B. D.

Changing Fractions to Decimals

1. Micah can have his bike fixed for $19.99, or he can buy the new part for his bike and replace it himself for $8.79. How much would he save by fixing his bike himself?

Decimal Word Problems

2. Megan buys 5 boxes of cookies for $3.75 each. How much does she spend?

Decimal Word Problems

1. Which costs the most per ounce, 60 oz of peanut butter for $5.40, 28 oz for $2.24, or 16 oz for $1.76?

Best Buy

2. Which is the least per pound, 5 lb of chicken for $9.45, 3 lb for $5.97, or 1 lb for $2.05?

Better Buy

1. Troy bought a worm farm and decided to raise worms to make money. The worm farm costs $110.00 initially and came with 200 worms and 500 worm capsules, each containing about 4 baby worms. He figures he can sell the worms to bait shops for $1.25 per dozen. How many dozen worms will he have to sell to begin to make a profit? Worms eat table scraps, so there are no food expenses?

Finding a Profit