Decimal numbers are numbers that include a decimal point (.) to show parts that are less than one. The digits to the right of the decimal point represent tenths, hundredths, thousandths, and so on.
Each place value after the decimal point is ten times smaller than the one before it. For example, tenths are larger than hundredths.
When adding decimal numbers, always line up the digits by their place values — ones under ones, tenths under tenths, and so on. This helps make sure that each digit is added correctly.
Always double-check that your decimal points are lined up before adding. Misalignment can lead to incorrect answers.
To add decimal numbers, align the decimal points, add each column of digits, and write the decimal point in the answer directly below the others.
3.45
+ 2.60
——————
6.05
Adding a zero at the end of a decimal (like changing 2.6 to 2.60) does not change its value. It only helps keep place values aligned.
When solving word problems with decimals, identify the quantities being added, write an equation, line up the decimals, and find the total. Make sure your answer makes sense in the context of the problem.
2.75
+ 1.60
——————
4.35
Always include units (like dollars, meters, or pounds) in your final answer when solving word problems with decimals.
After adding decimals, estimate or round the numbers to check if your answer is reasonable. This helps catch simple mistakes.
Estimation helps you see if your answer is too high or too low. It’s a quick way to check your work.