PRACTICE: Addition and subtraction
Practice
In this section we will practice using place value columns to set up a standard algorithm. This is useful to solve addition and subtraction problems, instead of using:
- place value models
- number lines
- partitioning to break our numbers up
We also looked at how to use a standard algorithm to solve addition or subtraction where we needed to regroup our numbers.
We also saw a mix of addition and subtraction problems of different lengths, where we may, or may not, need to do some regrouping.
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You might notice that sometimes the standard algorithm is called the 'vertical algorithm'. Let's think about why. When we use the standard algorithm, we line our numbers up in 'vertical' place value columns.
Apply
Question 1
Use a strategy to find $47-25$47−25.
Question 2
Find the value of $218+13$218+13.
Question 3
Find the value of $464-217$464−217.
When we use a standard algorithm, we need to make sure our digits are lined up so they are in the correct place. If we need to regroup, we regroup to the left for addition, and to the right for subtraction.