Composing a decimal means putting smaller place value parts together to make a whole or a larger decimal. Decomposing means breaking a decimal into its place value parts to see how each digit contributes to the number’s value.
Each place to the right of the decimal point represents a fraction with a denominator of ten, one hundred, one thousand, and so on.
In decimals, each place has a specific value that is ten times smaller than the place to its left. The pattern continues from tenths to hundredths, thousandths, millionths, and even billionths.
The place value chart for decimals never ends—it continues dividing by ten for each new place to the right.
To compose a decimal, add together the values of each place. This shows how individual parts combine to make one complete number.
When adding or writing decimals, always align the decimal points so that digits in the same place value line up vertically.
To decompose a decimal, break it apart into its individual place value parts. Each digit represents a fraction of ten based on its position.
Decomposing helps you understand that each decimal digit represents a specific part of one whole. This is useful when comparing, rounding, or estimating decimals.
Models such as grids, number lines, and base-ten blocks help you picture how decimals grow smaller as you move to the right. Each new place is one-tenth of the place before it.
Understanding very small decimals helps build a strong number sense for measurement, data, and scientific notation later on.