Decimal place value shows the position of each digit in a number and how much it is worth. Each place to the left is ten times greater, and each place to the right is ten times smaller.
The decimal point separates whole numbers from fractional parts. The value of each digit depends on its position relative to the decimal point.
Digits to the right of the decimal point represent parts of a whole. Each place is one-tenth the value of the place to its left.
As you move to the right, each digit’s value becomes ten times smaller. Knowing all the decimal places up to billionths helps you read, write, and compare very small numbers accurately.
When reading decimal numbers, say the whole number part first, then say “and,” followed by the decimal part as a fraction.
Do not say “point four five” when reading decimals in math sentences—use fractional names to show understanding of place value.
To compare decimal numbers, line up the digits by the decimal point and compare each place from left to right until a difference is found.
Adding zeros to the end of a decimal does not change its value (for example, 0.5 = 0.50). This helps when aligning numbers for comparison.
Rounding decimals means finding a value that is close to the original number but simpler to use. You look at the digit to the right of the place you are rounding to.
When rounding, remember: 5 or more, round up; 4 or less, stay the same. Always check which place value you are rounding to.