Mastering Integer Subtraction
An interactive guide with ✨ AI-powered help.
The Golden Rule of Subtraction
The most important rule to remember is: "Subtracting an integer is the same as adding its opposite."
a - b is the same as a + (-b)
This is often called the "Keep-Change-Change" method. You **Keep** the first number, **Change** the subtraction to addition, and **Change** the sign of the second number.
The Math Behind the Rule: Additive Inverse
The term "opposite" has a formal name in mathematics: the additive inverse.
The additive inverse of any number is the number that you can add to it to get a result of zero.
The additive inverse of 7 is -7, because 7 + (-7) = 0.
The additive inverse of -4 is 4, because -4 + 4 = 0.
So, when we say "add the opposite," we are really saying "add the additive inverse." This is the key that unlocks integer subtraction!
Visualize on the Number Line
Enter two integers below to see how subtraction works on the number line. We'll use the "add the opposite" rule to visualize the movement.
Test Your Skills!
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