Integer subtraction: Problem type 2

Introduction

In this lesson, the same rules of integer subtraction apply as discussed in previous lesson. Here problems with little higher level of difficulty are solved.

Example 1:

Subtract

−4 – (−9)

Solution

Step 1:

Rule: Two like signs become a plus sign

So, – (−9) = + 9;

So, −4 – (−9) = −4 + 9

Step 2:

The signs of the numbers are different. So, we subtract the absolute values of the integers.

|9| – |−4| = 9 – 4 = 5

Step 3:

The sign of the number with larger absolute value (9) is +.

We keep this sign with the difference obtained in above step

So, −4 – (−9) = −4 + 9 = +5

Example 2:

Subtract

8 – (−2)

Solution

Step 1:

Rule: Two like signs become a plus sign

So, – (−2) = + 2;

So, 8 – (−2) = 8 + 2

Step 2:

The signs of the number are same. So, we add the absolute values of the integers.

|8| +| 2| = 8 + 2 = 10

Step 3:

The sign of the numbers is +.

We keep this sign with the sum obtained in above step

So, 8 – (−2) = 8 + 2 = +10