How would you solve 427-316?

Most people educated in the past would simply use the usual subtraction working to arrive at the answer of 111.

But lately, in the USA, the Common Core Math approach gets very complicated and teaches an approach that even the father who has a “Bachelor of Science Degree in Electronics Engineering, which included extensive study in differential equations and other higher math applications” **cannot explain it, nor get the answer correct.**

See also the Common Core method of adding 26+17:

Is it really necessary to use “number bonds” to “skip-count by seven” to add 7+7?

I agree with the father above that in Maths, “**simplification is valued over complication”**. This is why I always teach the easiest to understand method and the shortest method to solve questions to my students. No point using a complicated method when a shorter and simpler method can give the same answer!

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The error in the first example was skipping from 127 to 107 and forgetting about 117.

Hmmm…I’m not sure if I should feel good about finding it.

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Thanks for commenting!

Yes, it is great to find the error. Do share this article with your friends to see if they can find it too!

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I don’t know; both the subtraction and addition methods seem to me like pretty good ways of doing the operations in your head. I mean, maybe you don’t need any help in adding seven to seven, but if I needed to put together 78 and 26 I’d certainly see my eye drawn to how 78 is 75 plus 3 and 26 is 25 plus 1 and

ohbut 100 plus three plus one is nice and easy, isn’t it?LikeLike

Good point! The number bond technique has its merits too I guess. Just hope the students won’t be confused by the terminology used.

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