Unit 2 Fun with Decimals!

Welcome to the world of decimals!

Lesson 2-1 Understanding Decimals

A decimal is a number that uses a decimal point and has one or more digits to the right of a decimal point.

Since I know that the places to the left of the decimal point are ones, tens, hundreds and thousands…..I can remember the places to the right of the decimal point as tenths, hundredths, thousandths……

Lesson 2-1 Understanding decimals

A decimal is a number that uses a decimal point. Each digit in a decimal number has a place and value. You can use a place-value chart to determine a digit’s place and value.

Place: 8 is in the thousandths place.Value: 8 thousandths, or 0.008.Standard form: 5.2684 Word form: five and two thousand, six hundred eighty-four ten thousandths.

Lesson 2-1 Comparing and Ordering Decimals You know how to compare and order whole numbers by looking at

digit place value. The greater the digit, the higher the value. You still compare and order decimals by looking at digit place value.

Lesson 2-2 Comparing and Ordering Decimals

Don’t forget!

< less than > greater than

The mouth is open to eat the bigger number!

Lesson 2-3 Rounding Decimals

Biggest difference between rounding decimals and rounding whole numbers!

Lesson 2-4 Estimating the sum and difference of decimals You can round each decimal to the nearest

whole number or dollar!

Lesson 2-4 Estimating Products and Quotients of Decimals

You can do the same as you would with whole numbers - round each factor or use compatible numbers!

Lesson 2-5

Adding and Subtracting Whole Numbers and Decimals

LINE UP THOSE DECIMAL POINTS!

Lesson 2-6 Multiplying Whole Numbers and DecimalsUse estimation and counting of decimal places to make sure your answer makes sense!

Lesson 2-7 Dividing a decimal by a whole number

Lesson 2-7 Dividing a decimal by a whole number

Lesson 2-8 Dividing by a decimal

Hop those decimals in your divisor to make a whole number and then hop your decimal in your dividend the same number of spaces!

Lesson 2-10Decimals and Powers of 10

Hop that Decimal Point!

.

Which way do I hop?

Positive power of 10

(Ex. 10³ = 1,000)

Negative power of 10

(Ex. 10 -³ = 0.003)

X

Multiply

÷

Divide

.

Move the decimal point the same number of places to the right as the exponent. Makes the number bigger!

Move the decimal point the same number of places to the right as the exponent.

Move the decimal point the same number of places to the left as the exponent.

Move the decimal point the same number of places to the left as the exponent. Makes the number smaller!

Multiplying by a Positive Power of 10

5 6 4 5 x 10³•

5,6 4 5

Multiplying by a Positive Power of 10

34654 x 105•

Lesson 2-11 Scientific Notation

A number written in scientific notation is expressed as a number that is greater than or equal to 1, but less than 10, multiplied by a power of ten.

_________ x 10

(must be ≥ 1 but < 10)

The power is the number of hops you took to make the whole number ≥ 1 but < 10

Lesson 2-11 Scientific Notation

Lesson 2-12 Solving Lesson 2-12 Solving EquationsEquations

with Decimalswith DecimalsHow can you solve decimal How can you solve decimal

equations?equations? Just as with whole number equations, Just as with whole number equations,

decimal equations can be solved by using decimal equations can be solved by using inverse operations inverse operations and the and the properties properties of equality.of equality.