Decimal Place Value
Mrs. Goulet wrote this number out on the white board. It read twenty-five thousand, two hundred forty-three and six thousandths. She asked Sarah to write this number in standard form. She wrote it correctly. What did it look like?
DEFINITIONOF A DECIMAL: A decimal is a number that is written using the base-ten place-value system. Each place value is ten times the place value to it's right.
Example 1: 9.87
WORD FORM: nine and eighty-seven hundredths
DECIMAL FORM: 9.87
EXPANDED FORM: 9 ones + 8 tenths + 7 hundredths
9.0 0.8 .07
Example 2:
A person timing you run says your time was sixty-seven and five tenths seconds. Write your time as a decimal.
sixty-seven and five tenths Note: the word and indicates the decimal point.
67 . 5
Example 3:
Car racing at the Indianapolis 500: Fastest Race Lap:
236.103 mph / 379.971 km/h,
Eddie Cheever, 1996
Write his time in words.
two hundred thirty six and one hundred three thousandths
2 3 6 . 1 0 3 Note: You read a decimal according to the last place value (in this case the
thousandths)
Guided Practice:
1. Write 40 hundredths using only tenths.
2. Write 1 one and 6 tenths using only tenths.
3. 1 one = ? hundredths
4. 3 ones and 7 tenths = ? tenths
5. A horse ran a lap in fifty-six and eight tenths seconds. Write the time as a decimal.
6. A germ is so small that you need a microscope to see it. It is 1/1000 of a millimeter. Write that number as a decimal and write it out in words.
7. If a decimal in expanded form is: 7 + 0.8 + 0.06 + 0.004 What is the number in decimal form?
8. Write the decimal in expanded form: three and 78 hundredths
9. A building is one hundred thirty seven and fifty-two meters tall. Write the height as a decimal.