Party. Elena is buying cups and plates for her party. Cups are sold in packs of 8 and plates are sold in packs of 6. She wants to have the same number of plates and cups. Find a number of plates and cups that meet her requirement.

How many packs of each supply will she need to buy to get that number?

Name two other quantities of plates and cups she could get to meet her requirement.

Tiles. A restaurant owner is replacing the restaurant’s bathroom floor with square tiles. The tiles will be laid side-by-side to cover the entire bathroom with no gaps, and none of the tiles can be cut. The floor is a rectangle that measures 24 feet by 18 feet.
What is the largest possible tile size she could use? Write the side length in feet. Explain how you know it’s the largest possible tile.

How many of these largest size tiles are needed?

Name more tile sizes that are the whole number of feet that she could use to cover the bathroom floor. Write the side lengths (in feet) of the square tiles.

Stickers. To celebrate the first day of spring, Lin is putting stickers on some of the 100 lockers along one side of her middle school’s hallway. She puts a skateboard sticker on every 4th locker (starting with locker 4), and a kite sticker on every 5th locker (starting with locker 5).
Name three lockers that will get both stickers.
After Lin makes her way down the hall, will the 30th locker have no stickers, 1 sticker, or 2 stickers? Explain how you know.

Kits. The school nurse is assembling first-aid kits for the teachers. She has 75 bandages and 90 throat lozenges. All the kits must have the same number of each supply, and all supplies must be used.
What is the largest number of kits the nurse can make?
How many bandages and lozenges will be in each kit?

What kind of mathematical work was involved in each of the previous problems? Put a checkmark to show what the questions were about.

Evaluation: What Kind of Problem?
1. For each problem, tell whether finding the answer requires finding a greatest common factor or a least common multiple. You do not need to solve the problems.
a. Elena has 20 apples and 35 crackers for making snack bags. She wants to make as many snack bags as possible and wants each bag to have the same combination of apples and crackers. What is the largest number of snack bags she could make?

b. A string of holiday lights at a store has three colors that flash at different times. Red lights flash every fifth second. Blue lights flash every third second. Green light flashes every four seconds. The store owner turns on the lights. After how many seconds will all three lights flash at the same time for the first time?

c. A florist orders sunflowers every 6 days, starting from the sixth day of the year, and daisies every 4 days, starting from the fourth day of the year. When (or on which day) will she order both kinds of flowers on the same day?

d. Noah has 12 yellow square cards and 18 green ones. All the cards are the same size. He would like to arrange the square cards into two rectangles—one of each color. He wants both the yellow and green rectangles to have the same height and to be as tall as possible. What is the tallest possible height for the two rectangles?

2. Explain how you know which problem(s) involves finding the greatest common factor.