Subtracting Mixed Numbers: 3 Easy Strategies for Kids (Number Line, Models & Equations!)

Need help solving mixed number subtraction problems like 3 ⅗ - 1 ⅕ ? This post (and video!) will guide you through THREE simple strategies to make subtracting mixed numbers a breeze for upper elementary students. We'll explore number lines, visual models, and equations, so you can find the method that works best for your learning style.

Watch the Video:

Why Subtract Mixed Numbers?

Before we dive into the how, let's talk about the why. Subtracting mixed numbers is a practical skill that pops up in real-life situations more often than you might think!

• Leftover Pizza: Figuring out how much pizza is left after a party.

• Home Renovation:  Calculating the length of wood needed for a project after some has been cut off.

• Measuring Workouts:  Tracking the distance covered during different parts of an exercise routine.

  
  

3 Strategies for Subtracting Mixed Numbers

Ready to tackle those mixed numbers? Let's explore three effective strategies:

1. Number Line Subtraction

Visual learners, this one's for you! A number line helps you see the difference between two mixed numbers.

• Plot the Numbers:  Mark both mixed numbers on a number line.

• Find the Distance: Count the spaces between the two numbers to find the difference.

• Tip: To make sure your whole number jumps are correct, think of the fraction equivalent to one whole (e.g., 5/5 = 1).

2. Subtracting with Models

Models provide a concrete way to visualize subtraction.

• Represent the First Number: Draw a picture to represent the first mixed number (e.g., circles for whole numbers and divided sections for fractions).

• Take Away: Cross out the amount represented by the second mixed number.

• Count What's Left:  The remaining parts represent your answer.

3. Using Equations

This is the standard algorithm for subtracting mixed numbers:

• Line Up:  Write the problem vertically, aligning whole numbers with whole numbers and fractions with fractions.

• Subtract Fractions: Subtract the numerators of the fractions, keeping the denominator the same.

• Subtract Whole Numbers:  Subtract the whole numbers.

• (Future Lesson!) Regrouping: If the top fraction is smaller than the bottom fraction, you'll need to regroup (borrow) from the whole number. We'll cover that in another video!

Learning Standards Connection:

This video aligns with the following Common Core standards:

• 4.NF.B.3c: Add and subtract mixed numbers with like denominators.

Let's make subtracting mixed numbers a piece of cake (or pizza)!

What strategy works best for you and your students? I found that having multiple strategies gives each students the choice to find one that works best for them!