Post 1a: Integer Operations (Addition and Subtraction)

(by Matthew M. with help from Sage the intrepid student dog)

Sage enters the door and sees a vast hall, much bigger than it looked from outside. As he tries to walk past the number line etched into the floor, he is stopped by an invisible force. Sage looks up an sees equations floating in the air involving integers. He wonders if this has something to do with crossing the room.

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"Integer operations" just means working with positive and negative whole numbers. 

The key question here is: Should the answer get bigger or smaller? Asking yourself this question will make it easy to tell when an answer isn't right. Don't worry if you find this confusing: Our intrepid canine student, Sage, is not sure about this yet.

Read and work along as our intrepid canine student Sage reviews how to work with Integers!

We'll look at four tricky spots: carrying, subtracting past zero, adding a negative, and subtracting a negative. For each one, you'll have the chance to turn someone's wrong answer into the right one, after a quick brush up of how it works.

First common problem: Forgetting to carry

Which one of these looks correct?

A) 36+8 = 34     B) 36+8 = 44

(It's B.) Let's use a moment of math scratchpad to look this and some other cases. You can make changes right inside it.

Sage is doing ok with this adding stuff.

How about you?

But we also have to look at subtraction:

Oof. Negative results! That was hard! Sage needs a nap in the sunshine.

Ok, maybe don't do that, but get a glass of water and see what we have in store next. Sage always gets confused when negative numbers are involved. A little practice seems in order:

Sage is starting to get the hang of it!

But there is one more thing here that always gives Sage trouble, it's when we subtract negative numbers.

Wow. You and Sage worked through 4 common situations where students get in trouble with integers. Well done! Sage feels like a master of integers now:

If you still have problems with these operations, we suggest you check out this article to brush up on the concepts, and then try again.

Drawing on lessons from school, Sage tries solving some of the equations floating around. Each time he does, he slides along the number line to the answer. Slowly, his confidence grows.

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