Integers: Remembering a Few Simple Rules

Rules for Working with Integers

Much of math involves working with integers – positive and negative numbers, and yet it is an area that most children struggle to understand. By remembering a few simple rules, you can help your children easily master the basics of positive and negative numbers.

Adding Integers

Adding integers seems difficult, but there are two rules that will work for every addition problem.

  • same signs = add the numbers, and keep the same sign                            (Ex: 3 + 2 = 5  or -3 + -2 = -5)
  • different signs = subtract the numbers, and keep the sign of the bigger number   (Ex: -3 + 2 = -1  or  3 + -2 = 1)

Subtracting Integers

Subtracting integers tends to be the trickiest operation for most children. However by following three steps, subtraction can be easier for children to master.

  • Change the subtraction sign to an addition sign
  • Then change sign of the second number
  • Finally follow the addition rules to get your answer
  • Example:  -3 – 2 =   becomes  -3 + -2 =    or   3 – -2 = becomes 3 + 2 =

Multiplying and Dividing Integers

When multiplying and dividing integers, the basic math fact remains the same.  The only thing that changes is the sign of the answer.  Two simple rules will help your child decide whether the answer is positive or negative.

  • same signs = positive answer  (Ex:  3 x 2 = 6  or -3 x -2 = 6)
  • different signs = negative answer   (Ex:  -3 x 2 = -6  or  3 x -2 = -6)

As your child begins to learn about positive and negative numbers, these basic rules can give them a good foundation for working with integers in the future.  I like to write these 7 rules on an index card for each child.  They can then keep the card in front of them during math time until they memorize the rules.

How do you help your child remember the rules for positive and negative numbers?

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