Subtracting Integers

Integers are subtracted in the same fashion as whole numbers, except that certain rules should be applied.

  • If you subtract negative integer from positive then just add numbers ignoring any minuses, i.e `color(blue)(a-(-b)=a+b)`.
  • If you subtract positive integer from negative, add numbers ignoring any minuses and then place minus in front of result, i.e. `color(green)(-a-b=-(a+b))`.

Example 1. Find `46-(-21)`.

`46-(-21)=46+21=67`.

So, `46-(-21)=67` .

Next example.

Example 2. Find `-35-21`.

`-35-21=-(35+21)=-56`.

So, `-35-21=-56` .

Example 3. Find `23-51`.

`23-51=-28`.

Another example.

Example 4. Find `-48-(-19)`.

`-48-(-19)=-48+19=19-48=-29`.

So, `-48-(-19)=-29` .

Final example shows how to subtract more than two integers.

Example 5. Find `-48-(-45)-34`.

We do such problems step-by-step.

First find `-48-(-45)`. `-48-(-45)=-48+45=-3`.

Now we are left with `-3-34`. `-3-34=-(3+34)=-37`.

So, `-48-(-45)-34=-37` .

Now, it's your turn. Take pen and paper and solve following problems.

Exercise 1. Find 36-(-21).

Answer: 57.

Exercise 2. Find -57-60.

Answer: -117.

Exercise 3. Find 100-69.

Answer: 31.

Exercise 4. Find -45-(-60).

Answer: 15.

Exercise 5. Find 65-(-34)-(-35)-21-(-45)-100.

Answer: 58.