1. 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 0.5 represents the fraction 5/10
The decimal 0.25 represents the fraction 25/100
What decimal is represented by the fraction 461/1000?
0.461

2. Significant Digits or Figures
Significant digits are the most important parts of the number
They tell you how precise a number or measurement is
They are the digits after the decimal point and after any zeros
Trailing zeros count as significant digits 4 3
significant digits

3. 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
tenths
ten thousandths
hundredths
thousandths

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

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

6. 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 =
0 07
x 3 =
One position behind decimal

7. 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 that new number by the whole number value of the second number (ignore decimal point)
0.08 ÷ 0.4 =
0 8
÷ 4 = 0.2
One position behind decimal

8. 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