Plus and Minus Numbers

In Mathematics plus and minus numbers are called directed numbers. One of the biggest stumbling blocks for children in High School Mathematics is dealing with plus and minus numbers. They keep mixing up the rules for addition and multiplication of directed numbers.

I came up with a way to solve this problem when I was a boy and it is how I have taught my own children.

In dealing with the addition of plus and minus numbers simply see numbers as belonging to either the plus army or the minus army. When two minus or two plus numbers meet they add to make their army bigger. When a plus meets a minus they kill each other.

Examples:

1) -2 -3 = -5

2) -8 +2 = -6

In dealing with the multiplication and division of plus and minus numbers the student must remember the following two rules:

1. When the signs are different the result is minus.

2. When the signs are the same the result is plus.

Examples:

1) -3 x 2 = -6 ( Note that if there is no sign in front of a number it is a plus number)

2) -5 x -4 = 20

3) -12 / 3 = -4

4) -35/ -7 = 5

I have also written an article which is published in HubPages titled Life and Death Mathematics which goes into the addition of directed numbers in more detail. Following is a link to that - Life and Death Mathematics

I also developed an interactive computer program to teach my own children all the fundamentals of arithmetic, when they were in primary school, which include dealing with directed numbers and learning tables.

My main incentive for developing this program was for them to master the basics in a methodical and consistent way and regardless of who was teaching them in school. I could see how methodology in schools changed from one year to the next which has resulted in many children nowadays leaving school without knowing their tables or being able to do the most rudimentary calculations without a calculator. The program is also patient and non-critical so the child does not pick up all of the negative vibes that parents can give off unwittingly while doing their best for their children.

All of my children mastered the basics of arithmetic in this way and have excelled at the subject. The program is available commercially and can be purchased by contacting me.