They look at the number of ones in the second number. In this example, it is 2. So they cross out 2 dots (ones) in their picture. Then count the number of dots that are not crossed out. This number is written in the ones column in their chart.
Let's use 375 - 152 as an example. The first thing the students need to do is draw the base ten blocks for the larger number. I also have the students draw a hundreds, tens, and ones chart to help them keep track of their work.
The last step is to circle their answer. This helps me clearly see their answer.
Here is a LearnZillion video that shows how to subtract 3-digit numbers without regrouping using the base ten strategy.
If you just want the LearnZillion quick code:
LZ4426
As always...
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