# Worksheet: Finding and Using the Lowest Common Multiple

Q1:

What is the least common multiple of 7 and 5?

Q2:

What is the least common multiple of 4 and 6?

Q3:

Find the LCM of 49 and 6.

• A165
• B294
• C104
• D55

Q4:

Find the LCM of 6, 15, and 40.

Q5:

Find the LCM of 4, 6, and 49.

Q6:

Find the LCM of 4, 18, and 46.

Q7:

Find the LCM of , and 4.

Q8:

List the next five common multiples after the LCM of 4 and 9.

• A72, 144, 216, 288, 360
• B2, 3, 4, 5, 6
• C72, 108, 144, 180, 216
• D2, 4, 6, 8, 10
• E36, 72, 108, 144, 180

Q9:

List the next five common multiples after the LCM of 2 and 16.

• A32, 64, 96, 128, 160
• B4, 6, 8, 10, 12
• C32, 48, 64, 80, 96
• D4, 8, 12, 16, 20
• E16, 32, 48, 64, 80

Q10:

Every 6 years, a group of university graduates organizes their own reunion. Every 9 years, the same university organizes an official reunion for its alumni. If both reunions took place in 2007, in what year will both reunions take place again?

• A2037
• B2061
• C2025
• D2022
• E2019

Q11:

A botanist waters one plant every 48 days and another every 40 days. If she waters both plants today, in how many days will she water the two plants on the same day again?

• Aafter 80 days
• Bafter 240 days
• Cafter 88 days
• Dafter
1 912
days

Q12:

Anthony goes to the supermarket every 14 days, and Elizabeth goes to the same supermarket every 21 days. If Anthony and Elizabeth meet at the supermarket on a particular day, how many days will pass before they meet each other again at the supermarket?

Q13:

At a school picnic, every child is given a yogurt, an apple, and a brownie. Yogurts come in packets of 8, apples in bags of 4, and brownies in packages of 6. When all the children have been served, they realise that they have used a whole number of packets of yogurt, a whole number of bags of apples, and a whole number of packages of brownies. What is the least number of students there could have been for this to happen?

Q14:

Emily goes to the library every 6 weeks. Molly goes to the same library every 7 weeks. If they met at the library one day, how long would it be before both of them are at the library in the same week again?

Q15:

A restaurant is promoting itself by serving a free drink to every 7th customer and a free meal to every 17th customer. Which customer will be the first to be served both a free meal and a free drink?

• A48th customer
• B17th customer
• C119th customer
• D24th customer
• E238th customer

Q16:

A normal speed printer prints an image every 42 seconds, and a more efficient one takes 14 seconds to print an image. If both printers start printing a document of identical images together, how many seconds will pass before the printers first complete printing out an image at the same time?

Q17:

Write three numbers that have an LCM of 210.

• A2, 5, 7
• B2, 15, 5
• C2, 15, 21
• D2, 7, 21
• E5, 15, 21