| Decimal
place value through ten thousandths
Place values of decimal numbers are determined by their position relative to the decimal point. The first number to the right of the decimal is the tenths' position, the second is the hundredths' position, the third is the thousandths', and the fourth is the ten-thousandths', and so on. Zeros to the right of the right-most digit of value are generally not expressed. Whole Number Decimal Number
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| Read and write decimal numbers | Numbers
- Decimal Numbers - In Depth
Numbers - Decimal Numbers - Examples Decimals and Integers - Decimal Numbers - Workout |
| Expanded form |
| Decimal notation |
| Estimate
and Round decimals
Decimal numbers are rounded in the same manner as whole numbers except that zeros are not needed to fill in the rounded positions. Look at the number to the right of the place to be rounded. If the number is 5 or greater, add one to the column to the left. If the number is less than 5, the column to the left remains the same. Then remove all the digits to the right of the place to be rounded. |
Estimating
and rounding decimals
Estimating and rounding decimals - In Depth Estimating and rounding decimals - Examples Estimating and rounding decimals - Workout |
| Add
decimals
Line up the decimal points and add as if the numbers were whole numbers. If a number doesn't have a decimal point, the decimal point is understood to be at the ar right of the number. |
Adding/subtracting decimals Adding/subtracting decimals - In Depth Adding/subtracting decimals - Examples Adding/subtracting decimals - Workout |
| Multiply
decimals
Multiply decimal numbers as if they were whole numbers. To find the the correct place to put the decimal point in the answer, count the total number of digits to the right of each decimal point and count off that many places in the answer. Begin counting from the right, moving to the left. |
Multiplying decimals Multiplying Decimals - In Depth Multiplying Decimals -Examples Multiplying Decimals-Workout |
| By zero |
| By powers of ten |
| Divide
whole number into decimal
To divide a decimal by a whole number, divide then put the decimal in the quotient directly above the decimal point in the dividend. |
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| Divided
decimal by decimal
To divide a decimal by a decimal, move the decimal point in the divisor all the way to the right to make a whole number. Then move the decimal point in the dividend the same number of places to the right. Divide and put the decimal in the quotient directly above the decimal point in the dividend. |
Dividing
Decimals
Dividing Decimals - In Depth Dividing Decimals - Examples Dividing Decimals - Workout |
| Repeating decimals |
| Exponents
An exponent is a number that tells how many times the base is used as a factor. In 3^2, 3 is the base and 2 is the exponent. When writing numbers the exponent is written to the right and above a number. On the computer the sign for an exponent is ^. |
Exponents
Exponents - In Depth Exponents - Examples Exponents - Workout Exponential Calculator |
| Squares
and square roots
The square of a number is that number times itself. Finding the square root of a number is the inverse operation of squaring that number. Perfect squares are: 1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144 |
Square
roots
Square roots - In Depth Square roots - Examples Square roots - Workout Square Root Calculator Print this page for help |
| Solve word problems with decimals |