1. Decimals Review

2. Decimals Decimals are a type of fractional number The denominator is always a power of 10 A decimal point is used to show that it is less than 1 The decimal.5 represents the fraction 5/10 The decimal.25 represents the fraction 25/100 What decimal is represented by the fraction 461/1000?0.461

3. Significant Digits or Figures They are the digits after the decimal point and after any zeros Trailing zeros count as significant digits 0.000567 significant digits34 0

4. Significant Digits or Figures Significant digits are the most important parts of the number They tell you how precise a number or measurement is

5. Positions Positions tell us how much each digit is worth, like they do for whole numbers They are the number of spaces each digit is behind the decimal point 0. 0 0 0 0 tenths hundredthsthousandths ten thousandths

6. Math With Decimals Four basic functions Add Subtract Multiply Divide

7. Addition Line up the decimal points to make sure everything is in the correct column Add like you would integers 0.587 + 0.036 = 0.587 0.036 + 0.623

8. Addition - Let’s Try It! 0.4 + 0.6 = 0.4 0.6 + 1.0 0.27 + 0. 05 = 0.27 0.05 + 0.32

9. Subtraction Line up the decimal points to make sure everything is in the correct column Subtract like you would integers 0.587 - 0.036 = 0.587 0.036 - 0.551

10. Subtraction - Let’s Try It! 0.7 - 0.3 = 0.7 0.3 - 0.4 0.27 - 0. 09 = 0.27 0.09 - 0.18

11. Multiplication Move the decimal point of the first number to the left one space for each position behind the decimal point of the second number Multiply that new number by the whole number value of the second number (ignore decimal point) Make sure to fill in any missing zeros 0.07 x 0.3 = x 3 = 0.021 One position behind decimal 0 070

12. Multiplication Examples 0.61 x 0.2 = One position behind decimal 0.0048 x 0.04 = Two positions behind decimal x 2 = 0.122 0 610 x 4 = 0.000192 00 00480

13. Multiplication - Let’s Try It! 0.01 x 0.1 = 0.09 x 0.02 = 0.4 x 0.007 = 0.33 x 0.2 = 0.012 x 0.7 = 0.5 x 0.001 = 0.001 0.0018 0.0028 0.066 0.0084 0.0005

14. Division Like multiplication, but move the decimal point of the first number to the right one place for each position behind the decimal point of the second number Divide the new number by the whole number value of the second number (ignore decimal point) 0.08 ÷ 0.4 = One position behind decimal ÷ 4 = 0.2 0 80

15. Division Examples 0.61 ÷ 0.2 = One position behind decimal 0.0048 ÷ 0.04 = Two positions behind decimal ÷ 2 = 3.05 6 10 ÷ 4 = 0.12 00 480

16. Division - Let’s Try It! 0.01 ÷ 0.1 = 0.09 ÷ 0.02 = 0.4 ÷ 0.008 = 0.33 ÷ 0.2 = 0.009 ÷ 0.03 = 0.56 ÷ 0.07 = 0.1 4.5 50 1.65 0.3 8

17. Review Decimals are fractional numbers where the denominators are powers of 10 Significant digits tell you how precise the number is Decimals add and subtract like integers Multiplying two decimals makes a smaller decimal Dividing two decimals makes a larger number