Line ‘em up or Count ‘em up Decimals Line ‘em up or Count ‘em up

Unit Overview By the end of this unit, you should be able to: Represent decimals on a number line Compare and order decimals Round decimals Use estimation to approximate an answer Add, subtract, multiply, and divide decimals

Representing Decimals Numbers to the right of the decimal point are called decimals. Decimals represent numbers that have a value between to whole numbers.

Write a Decimal in Word Form 1 7 5 4 2 17.542 Seventeen and five hundred forty-two thousandths To write in word form, follow these steps: Write the number to the left of the decimal. Write “and” where the decimal point is. Write the number that is to the right of the decimal point. Write the place value of the digit furthest to the right.

Write a Decimal in Word Form 8 2 5 .825 eight hundred twenty-five thousandths To write in word form, follow these steps: Write the number to the left of the decimal. Write “and” where the decimal point is. Write the number that is to the right of the decimal point. Write the place value of the digit furthest to the right.

Write a Decimal in Word Form 1 6 0 8 16.08 Seventeen and eight hundredths To write in word form, follow these steps: Write the number to the left of the decimal. Write “and” where the decimal point is. Write the number that is to the right of the decimal point. Write the place value of the digit furthest to the right.

Your Turn – Write these decimals in word form 1) 7.17 seven and seventeen hundredths 2) .068 sixty-eight thousandths 3) 9.0769 nine and seven hundred sixty-nine ten-thousandths Tips Only put hyphens (-) in the numbers 21 through 99 Don’t use commas Be sure of your place value

Write a decimal in standard form Standard form is just the usual way we write numbers. Thirty-five and ninety-six ten-thousandths 3 5 0 0 . 9 6

Your Turn Write three and eighty-five thousandths in standard form. 3.085 Write five tenths in standard form. 0.5 Write forty-one and sixty-two hundredths in standard form. 41.62

Your turn – Challenge problem Write this number in standard form: one hundred two ten-thousandths 0.0102 *Remember the word “AND”! one hundred AND two ten-thousandths= 100.0002 Totally different!

Write a decimal in Expanded form Expanded form is a sum of the products of each digit and its place value. (???) Basically, take each digit of the number and multiply it by its place value position. Then add all of those up. For example: 32.14  Take the 3 times 10 because it is in the tens place. + Take the 2 times 1 because it is in the ones place. + Take the 1 times .1 because it is in the tenths place. + Take the 4 times .01 because it is in the hundredths place. Looks like this: (3 x 10) + (2 x 1) + ( 1 x .1) + (4 x .01) When you solve it, you get the original number: (3 x 10) + (2 x 1) + ( 1 x .1) + (4 x .01) (30) + (2) + (.1) + (.04) 32.14

Your Turn- Write this number in expanded form Eleven and three tenths 11.3

Your Turn- Write this number in expanded form Two and five hundredths 2.05

Your Turn- Write this number in expanded form Thirty-four and sixteen hundredths 34.16