1. Introduction to Decimals
Section 5.1
Introduction to Decimals

2. Decimal Notation Used to denote a part of a whole.
Numbers written in decimal notation are called Decimal Numbers, or simply Decimals.
The decimal number has three parts.
Whole Number Part
Decimal Part
Decimal Point

3. Write a Decimal in Words
Steps
Write the whole number part
Change decimal to the word ‘and’.
Write the decimal part as a whole number.
End with the place value of the last digit.

4. Example
Translate the decimal into words. 2,

5. Example
Translate the decimal into words

6. Write the Words in Decimal Format
Steps
Find the word and, translate it into a decimal.
Translate the words before and as a whole num.
Find the last word on the right side of and, that is the number of spaces you need to fill.
Translate the words after and, into the spaces you have created.

7. Example
Translate the word into decimals. Fourteen thousand twenty-two and six hundred millionths.

8. Example
Translate the word into decimals. Two hundred fifteen and two hundred fifteen hundred thousandths.

9. Decimal → Fraction Steps Move whole number to the side, a
Count the number of places after the decimal, n
Place decimal number (without decimal) in the numerator.
The denominator will be a 1 with n zeros.
Simplify the fraction
Bring whole number back in, a.

10. Example
Write in fraction form.

11. Example
Write in fraction form.

12. Example
Write in fraction form.

13. Comparing Decimals Compare digits in the same places left to right.
When two digits are not equal, the number with the larger digit is the larger decimal.
If necessary, insert 0s after the last digit of the decimal point to continue comparing.

14. Example Insert < , > or = to form a true statement.

15. Example Insert < , > or = to form a true statement.

16. Rounding Decimal Steps Locate the digit of the place value given.
Look at the number to the right
If the number is a 0, 1, 2, 3 or 4 leave the digit alone.
If the number is 5, 6, 7, 8 or 9 add one to the digit
Replace all the numbers to the right of the given digit with zeros.

17. Example
Round 0.64 to the nearest tenth.

18. Example
Round $5.78 to the nearest dime.