Addition Numbers & Operations in Base 10

210 + 50 = 710

tom fleming 1

How do you teach kids to add numbers? Does it help kids avoid this mistake?

Thanks to Tom Fleming for the submission.

6 replies on “210 + 50 = 710”

Write the problem vertically, not horizontally. Ask students to solve it “with your head”. Open a discourse to promote computational fluency. By having regular “number talks” students will be more apt to use math reasoning when they solve problems on paper.

With my children (my biological kids), I have the foundation that I talk about place value A LOT. So for addition I tell them to make sure the numbers are lined up by place value and start adding with the ones places first (wanna bet that the student above did this addition left-to-right?).

With my students (high school), I use the phrase “reality check”. Always reality-check your answer after you work a problem. With abstract numbers, money is the best analogy. If you’ve got $210 dollars and then you earn another $50, are you going to have $710? Does that sound right?

We do a lot of number talks as Amy mentioned above that have students focusing on place value in a meaningful sense. I prefer to write problems (of any type) horizontally, however a student who has a strong foundation in numbers base 10 would be able to write it exactly as it is in the picture and still get the correct answer of 260.
Great example bc I see this all of the time!

I remember back when I was learning addition I was confused about how to write addition problems because since we read from left to right I thought that I should write out my numbers from left to right. What helped me was having a teacher explain place value and how 50 and 500 are very different. Also, by being shown that I should wright my number from right to left and then also work the problem from right to left also really helped me.

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