Question

can somone explain this problem to my son. Even on a numberline?

"Subtract -6 from 5"

I told him the answer is -13....He thinks its -1 and convinced of it.

Answer 1

So, in order to do this, you have to read the problem carefully. Also, you have remember that if you subtract a negative number, it turns into addition: -(-) = +

Answer 2

And because it is "subtract -6 FROM 5", it is 5 - (-6). The two negative signs turn into a positive sign and just add the 2 numbers: 5 + 6 = 11

Answer 3

5 -(-6) = 11

http://www.wolframalpha.com/input/?i=5-%28-6%29 (There's a number line here)

Answer 4

you son seems to be adding...not subtracting
-6 + 5 or 5 + (-6) = -1

and I don't even know where you came up with -13

Answer 5

We were both wrong iwillrektyou and Agent_A were right...Thanks for that number line. Where did you find it. REAL COOL thanks.

Answer 6

he just needs to learn the sign rules for adding/subtracting numbers. But be careful, because there are different sign rules for multiplying/dividing.

Answer 7

You can go to a website: http://www.wolframalpha.com for number lines and more. Glad to have helped!

Answer 8

but be careful...he needs to learn how to do it...not just the answers

Answer 9

Thanks; You guys broke up a household melt down. We are all now looking at this computer wondering why we were both wrong. Thanks again, and whom ever posted that multiplication is not the same, for some reason, he's just not understanding a negative being subtracted from a positive because visualizing it is really tough. TKS

Answer 10

try this..
https://www.khanacademy.org/math/arithmetic/absolute-value/adding_subtracting_negatives/v/adding-subtracting-negative-numbers

Answer 11

Thanks

Answer 12

@tough there's a neat way to visualize subtraction on the number line. For example we want to do the subtraction 5-3. Of course we know the answer is 2 but how can we see it on a number line?

Well, we see that if we start from the point 3, you need to make 2 steps to the right to get to 5. So the answer is 2 (or +2 if you like).

You can use the same idea with negative numbers. We want to subtract -6 from 5. [5-(-6)]
That's the same as asking:

Starting from the point -6 how many steps does it take to get to 5?
We could count the steps and we would find that it takes 11 of them. But we could also say that it takes 6 steps to get to 0, and 5 more to get from 0 to 5. This is where the equality:

5-(-6) = 5 + 6 comes from.

That's pretty neat, but what happens if want to calculate 3 - 5? Well it still takes two steps, but now in the direction of the negative numbers.

So we say that 3 - 5 = - 2