Decimals

NZ Level 4

Subtract single digit numbers with decimals in tenths or hundredths

Lesson

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:

Tens | Units (ones) | . | Tenths | Hundredths |
---|---|---|---|---|

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.

Remember!

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.

Evaluate $2.75-1.75$2.75−1.75.

Understand addition and subtraction of fractions, decimals, and integers