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Text From the Video
Now we are going to learn how show regrouping by using a shorter way to write out the problem. Look at the first example on the left. When we subtract, instead of writing out the long version of our regrouping like we did with 40 plus 10, we usually just cross out the digit in the tens place and make it one less. Look at the second box. Here I crossed out the five and made it a four. We know that the four is in the tens place so the value of the 4 is 40 but we write it as 4. Then we take the ten we borrowed and add it to the one that is in the ones place by putting a 1 in front of the ones digit to make 11. The one stands for 10. The 10 is added to the 1 that is there to make 11.
Now look at the example on the right. Here we regrouped by taking 10 from the 60 and making 50 plus 14. Now look at the box next to it. Here I showed it in the short way. I crossed out the 6 and made it a red 5. We know that the 5 is in the tens place so the value of the 5 is 50 but we write it as 5. Then we take the ten we borrowed and add it to the ones place by putting a 1 in front of the ones digit to make 14. The one stands for 10. The 10 is added to the 4 that is there to make 14.
Here are two more examples to look at. Pause the program and look at them carefully to see if you understand them. If you understand the short way to write the subtraction with borrowing problems then start the video and we will move to the next page to practice.
On this page it’s your turn to practice. Write these problems down on your paper, and then show how to regroup them and figure out the answer. You should use your base ten blocks to help you. Stop the video while you work.
Here are the answers. How did you do? If you made a mistake, go back and try it again. When you get them all correct, you can move on to the practice and the assignments tabs.