How do you subtract integers?

There are a few key methods to add and subtract integers. The first is easy to use but takes more time and thought (less automatic with practice). It is the number line method. Imagine (or draw!) a number line with 0 at the middle and negative numbers extending to the left. Now when you add a number, go to the left if it is negative and the right if it is positive to arrive at the answer. When subtracting do the opposite (as the subtraction sign negates the value of the number). For example, 3 - (-4) can be thought of as follows. Begin at positive 3. Now move 4 to the right (minus a negative is to the right). We end up at positive 7, the answer.

Another method is to change all subtraction problems to addition problems and learn to add any combination of integers (two positive, two negatives, one of each, and with 0). Generally:

a - b = a + (-b).

For examples:

3 - (-4) = 3 + -(-4) = 3 + 4 = 7.

-2 - 3 = -2 + (-3) = -5.

2 - 1 = 2 + (-1) = 1.

Note that the sum of two positive numbers is the sum of their absolute values. The sum of two negative numbers is the inverse of the sum of their absolute values. In other words, two positives become more positive and two negatives become more negative. Further, adding 0 does nothing to the number (additive identity).

Finally, when confronted with both a positive and negative number, whichever has the larger absolute value will be the sign of the result. Then take the difference in absolute values and apply that sign to the result.


My improvement is here:

The above is right, and it's for subracting signed (positive +, and negative - )integers. Some people might not know much about signed integers, so I try to give some improvement on just basic/plain integers.

Basically in order to subtract, you need to know how to add to see if you have done it right.

Now consider I have a basket of many apples. I could take some, say 5 out of the basket, hence I have subtracted 5 apples from the basket. I may or may not even know how many apples are left. In order to know how many are left I would need to initially know how many were in the basket to start with. If there were 8 apples in the basket to start with and I took a group of 5 out, then I have a group of 3 apples left in the basket because 8 - 5 = 3 since the basket originally contained the two groups of: 5 apples and 3 apples combined together, mathematically this is noted with addition: 5 + 3 = 8. We see that if you subtract one group (either the group of 5 or the group of 3) from 8, you will have the other group left.
How do you subtract intergers?
subtracting integers with tiles

to add integers, we combine group of tiles

to subtract integers, we do the reverse:


recall the equal numbers of red and yellow tiles model 0

for example:,(-5)+(+5)=0

adding 0 to the pair doesnt change its value.

for example:,(-3)+0=-3

to use tiles to subtract integers, we model the first integer, then take away the

number of tiles indicated by the second integer.

we can use tiles to subtract (+5)-(+9)=

answer: -4

by:Izabela torbinski