Mental Math: Digital Root Extraction

5 Steps

Step 5: Summary

Digital roots are a fun trick to amuse the nerdiest of your friends, and can be a useful tool in checking peoples math, especially mental math. I hope you enjoyed this math tutorial, and please, Please, PLEASE, rate and comment, and of course let me know if there is something you would like me to try and write an instructable on.

Thanks,
Purduecer
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mluft says: Aug 29, 2009. 6:19 AM
so, i am a 4th grade teacher and i'm teaching my students about digital root. i'm teaching them that it is a tool to use to check computation. i have a parent all up in my face saying it is too abstract for 4th graders and it is some new-fangled crap i'm teaching that is going to screw up her kid's understanding of math for life. i've searched and searched for something, anything to help her understand, but no luck. any ideas?
purduecer (author) in reply to mluftSep 2, 2009. 5:29 AM
In case you didn't know already, you can find out more about the digital root here. Digital roots are a topic that is indeed fairly abstract in math, but as you mentioned, they can be a quick but useful way to check hand computations. If I were you, and trying to explain to the parent, I would mention simply that you're teaching your kids a helpful shortcut for finding the remainder, and remind the parent that when they add all the digits together to see if a number is divisible by 9, they are in fact already taking the digital root.

Hope that helps, let me know.