Regrouping With Zeros

Aloha friends! I am so happy it is Thursday evening!!!  Tomorrow is Friday already and I am looking forward to some fun activities I have planned for my class.  I promise I will share all the fun this weekend.

Today is just a quick post to share what we did today in math.  Our school is using the Go Math series and it is Common Core aligned.  This is the third year using it and I finally feel like I have  grasp on some of the alternative methods they use to teach students addition and subtraction.

Today we were working on triple digit subtraction with zeros.

This is the standard method that the series shows and how we all learned 
growing up. This way however is so confusing for many of my students!
They always make the same mistake.

Here's an example.  
They know if they don't have enough ones to borrow a ten.

They don't have any tens so they borrow a hundred.  
They regroup in the tens place,

but they always forget to take from the ten BEFORE 
they add a ten to the ones place!

So I changed it up today and decided to show them
a way that might make more sense.

We reviewed that 400 is the same as 40 tens.

So we took away one ten and gave it to the ones.

They caught on so quick and made very few mistakes!!

Even my strugglers were very successful with this method.  
I hope it really sticks with them and makes subtracting 
zeros a much easier process.

Do you teach this method or other ways besides the standard algorithm?  I know Common Core is pushing others to find new strategies.  I hope you can add this one to your list.


  1. I don't teach math anymore, but I was presenting about using iPads at a math workshop and had to watch the opening speaker. He was all about teaching kids mental math and learning to be flexible with numbers and do things in ways that are easiest. One of the things he said is that instead of doing regrouping with problems like these (because the kids mess up and it takes a long time) they can try to eliminate the need. So if the problem is 400-263, that is the same difference as 399-262 (one away from each) there is no regrouping and it can be solved really easily.

    Literacy Spark

    1. That is so smart!! I've never really thought about teaching the strategy to kids quite this way. Makes perfect sense! :)

      Mrs. Beattie's Classroom

  2. That totally makes sense, but I never would have thought about it like that! Great gob thinking "out of the box"...LITERALLY!!

    The Resourceful Apple

  3. Thanks for sharing! I will be showing my students this strategy Monday for sure!!!
    More Than Math by Mo

  4. I use go math too and this lesson is coming up I think so I can't wait to try the method !!

  5. Totally taught this lesson today too! I am gonna show them this strategy when we get back from the weekend! Thanks for sharing!

  6. I've used this for several years. No more problems with kids, just parents who can't understand.

  7. I've used this for several years. No more problems with kids, just parents who can't understand.

  8. This is a great strategy to use! We are piloting Go Math this year and its taking some time to get used to. We should be doing that his sometime next week. Good thing I found this post first!

  9. I saw this strategy on YouTube it was called boxing in. My kiddos really got it last year. I think we're about ready to learn it this year. Thanks for the reminder!

  10. I used that strategy last year and my kiddos really got it. When I get to subtraction I'll definitely be going back to it!

    Success in Second Grade
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  11. This is the way I learned to do subtraction when regrouping with 0's as a child way back in the 70's. I rarely see anyone use this technique. I have used it for many years when teaching this skill because that is how I learned it. I make sure it isn't the only way I teach to work this type of problem but I do make sure I introduce it. I have always had some students who grabbed it and used it solely while others would use another technique.

  12. Two thumbs up for your ingenuity! You go girl!

  13. Two thumbs up for your ingenuity! You go girl~

  14. I love this strategy! How much simpler than putting 10 and then crossing it out and putting 9 on everything! Looking forward to teaching this to my 3rd graders as we regroup with 4-digit numbers next week! Thank you!


Mahalo Nui Loa For Commenting!!

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