When we subtract numbers with decimals, we follow the same process as working with whole numbers, except we have more columns that come after the decimal point:
Whole numbers don't have any decimal values, so we can think of them as having zeros after the decimal point. For example, we could rewrite $87-23$87−23 as $87.00-23.00$87.00−23.00 to two decimal places. The process for solving decimals is just the same as for whole numbers. Let's watch a video to see how using decimals with values in the tenths and hundredths places.
In our second video, we are going to work through a subtraction where we need to regroup. When we are subtracting using a place value system (e.g. a vertical algorithm) and need to take a larger number away from a smaller number, we need to exchange a value from the previous place. For example, we could exchange $1$1 tenth for $10$10 hundredths. Subtracting decimal values uses the same process as with whole numbers, only now there are values in the columns after the decimal point. Let's take a look at this process in more detail.
We always start our calculations from the smallest place value column.
Evaluate $0.73-0.51$0.73−0.51. Write your answer as a decimal.
Evaluate $6.61-4.42$6.61−4.42. Write your answer in decimal form.