3.4: Division

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Amy Lagusker
College of the Canyons

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Model Division with Repeat-Subtraction

Example \(\PageIndex{1}\)

Leslie has 15 cookies to share with her friends. Each friend wants three cookies. How many friends can Leslie share her cookies with?

Solution

\(15-3=12-3=9-3=6-3=3-3=0\)

There are five groups of cookies, so Leslie is able to share with five friends.

This procedure is called Measurement Division. Measurement is any movement across the number line. On the number line, we are starting at 15 and moving down to zero by three’s.

Model Division with Sharing

Example \(\PageIndex{2}\)

Charlie has 15 balloons and three children. How many balloons does each child receive?

Solution

Each child receives five balloons.

This procedure is called Sharing Equally OR Partitive Division. Think of it like using the distributive property. Charlie is equally distributing a balloon to each child. Once each child has one balloon, Charlie then equally distributes another round of balloons to each child. Charlie stops when he runs out of balloons.

Partner Activity 1 - Dividing by Zero

What is \(5 \div 0\) also written as \(\dfrac{5}{0}\)? Why?

What is \(0 \div 5\) also written as \(\dfrac{0}{5}\)? Why?

What is \(0 \div 0\) also written as \(\dfrac{0}{0}\)? Why?

**Ноw would you explain dividing by zero to a 4th grader??

Practice Problems

Sophie needs to pass out papers to her coworkers. She has 28 papers and each coworker needs four papers. How many coworkers does she have? What type of division is this?
Later that day, Sophie speaks to ten other coworkers who need different papers. She runs off 30 copies. How many papers did each coworker receive? What type of division is this?