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Bran Hicks M.Ed.

How to Subtract Integers Using the KIO (Keep, Inverse, Opposite) Method

When it comes to subtracting integers, especially for students who struggle with number operations, the Keep, Inverse, Opposite (KIO) method offers a simple and reliable approach. By breaking the process into clear steps, students can confidently solve subtraction problems without confusion. This method is especially effective for students with ADHD or specific learning disabilities, as it simplifies complex subtraction into an easy-to-follow format.



 

What You Will Learn

  • The step-by-step process of subtracting integers using the KIO method.

  • Practical tips for teaching this method to students with diverse learning needs.

  • Example scenarios to reinforce understanding of the KIO method.


Steps for Subtracting Integers Using the KIO Method

1. Keep the First Number (Minuend)

To start, keep the first number exactly as it is. This means you don’t change the sign of the first integer in the subtraction equation.

Example:If the problem is 7−(−3), you keep the 7 exactly as it is.


2. Inverse the Subtraction Sign

Next, inverse the subtraction sign. This means you change the subtraction sign to an addition sign. By converting the problem into an addition equation, you make the next steps easier to manage.

Example:In the problem 7−(−3), the subtraction sign between the 7 and −3 becomes an addition sign, transforming the problem into 7+(−3).


3. Opposite the Second Number (Subtrahend)

Now, you need to change the second number to its opposite. If the second number is negative, you make it positive, and if it’s positive, you make it negative.

Example:In the problem 7+(−3), you change the −3 to its opposite, which is +3. Now the equation becomes 7+3.


4. Add the Two Numbers

Finally, add the two integers. At this point, the problem is a simple addition, making it easier for students to solve.

Example:For 7+3, the solution is 10.

Final Example

Let’s go through another example using the KIO method:

Problem:8−(−5)

  • Keep: 8

  • Inverse: Change the subtraction sign to +, so the equation becomes 8+(−5).

  • Opposite: Change −5 to its opposite, +5. Now the equation is 8+5.

  • Add: Solve 8+5, which gives you 13.


Student Scenario

Imagine a student named Alex, who often feels overwhelmed when subtracting negative numbers. By introducing Alex to the KIO method, you give them a consistent and structured approach to follow, reducing anxiety and boosting confidence. For instance, Alex encounters −4−(−7) and initially feels confused. However, following the KIO steps:

  • Keep: −4

  • Inverse: +

  • Opposite: +7

Alex easily arrives at the answer: −4+7=3. By breaking the process down, Alex can now solve integer subtraction problems accurately.


Teaching Tips for Students with Diverse Needs

  • Visual Supports: Use visual aids like number lines to show how flipping the sign changes the direction of movement on the line. This helps students understand the concept of opposites.

  • Guided Practice: Start with simple problems and gradually increase difficulty. Encourage students to verbalize each step as they solve the problem.

  • Memory Aids: Use mnemonic devices like “Keep, Inverse, Opposite” to help students remember the process.

  • Repetition and Reinforcement: Provide plenty of practice problems to build familiarity and confidence.


The KIO method simplifies integer subtraction, making it accessible for all learners, especially those who may struggle with math concepts. By teaching students to keep the first number, inverse the sign, and use the opposite of the second number, you're setting them up for success in solving integer problems with ease.


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