Worksheets · Pre-Algebra

Least common multiple worksheet

Take every prime that appears, as many times as it appears in whichever number uses it most. That is the smallest number all of them go into, and it is what a common denominator is.

Select your difficulty

Pick more than one for a sheet that mixes them.

Free math worksheets at sigmaprep.io/worksheets© 2026 Sigma Prep

Sigma Prep · sigmaprep.io/worksheets

Name

Least Common Multiple

Date Period

Find the least common multiple.

  1. Find the LCM of 18 and 13
  2. Find the LCM of 17 and 20
  3. Find the LCM of 20 and 15
  4. Find the LCM of 17 and 18
  5. Find the LCM of 16 and 20
  6. Find the LCM of 16 and 16
  7. Find the LCM of 14 and 16
  8. Find the LCM of 14 and 14
  9. Find the LCM of 16 and 13
  10. Find the LCM of 16 and 19
  11. Find the LCM of 15 and 14
  12. Find the LCM of 13 and 16
  13. Find the LCM of 17 and 19
  14. Find the LCM of 18 and 17
  15. Find the LCM of 19 and 14
  16. Find the LCM of 18 and 16
  17. Find the LCM of 19 and 20
  18. Find the LCM of 14 and 19
  19. Find the LCM of 14 and 15
  20. Find the LCM of 16 and 14

Free math worksheets at sigmaprep.io/worksheets© 2026 Sigma Prep

Sigma Prep · sigmaprep.io/worksheets

Name

Least Common MultipleAnswer keyVersion 1

Date Period

Find the least common multiple.

  1. Find the LCM of 18 and 13234
  2. Find the LCM of 17 and 20340
  3. Find the LCM of 20 and 1560
  4. Find the LCM of 17 and 18306
  5. Find the LCM of 16 and 2080
  6. Find the LCM of 16 and 1616
  7. Find the LCM of 14 and 16112
  8. Find the LCM of 14 and 1414
  9. Find the LCM of 16 and 13208
  10. Find the LCM of 16 and 19304
  11. Find the LCM of 15 and 14210
  12. Find the LCM of 13 and 16208
  13. Find the LCM of 17 and 19323
  14. Find the LCM of 18 and 17306
  15. Find the LCM of 19 and 14266
  16. Find the LCM of 18 and 16144
  17. Find the LCM of 19 and 20380
  18. Find the LCM of 14 and 19266
  19. Find the LCM of 14 and 15210
  20. Find the LCM of 16 and 14112

Free math worksheets at sigmaprep.io/worksheets© 2026 Sigma Prep

How to do these

The LCM of 6 and 8

  1. 6 is 2 x 3, and 8 is 2 x 2 x 2.
  2. Take three 2s and one 3.
  3. That is 24.

The answer is 24.

Where students go wrong

Multiplying the two numbers together. That always gives a common multiple, but it is only the least one when the two share no factors; 6 times 8 is 48, and 24 gets there first.

Also called LCM, lowest common multiple or common denominator.

Questions about these worksheets

Yes. Every least common multiple sheet is free to print and free to download as a PDF. There is no account to make, no email to hand over and no limit on how many you take.

Yes. The answer key prints on a second page, and you can choose whether it shows each question beside its answer or just the answers in a list.

Yes. Print straight from the page, or download the PDF and print that. The sheet is laid out for paper rather than squeezed off a screen, so there is room to work under each question, and the answer key comes out on its own page.

Pre-Algebra is usually taken around 7th or 8th grade, though schools vary and plenty of students meet it earlier or later. Pick the difficulty rather than the grade: the easy level suits a first lesson on it, the hard level suits review before a test.

Yes, as many as you like. The questions are built fresh each time rather than picked from a fixed set of files, so pressing Generate gives a new sheet. That is what you want for a second class, a retake, or two students sitting next to each other.

That is the closest comparison, and Kuta Software is good software. It is also paid software you install on a computer. These worksheets run in a browser tab for free, with no account and nothing to install. Like Kuta, the least common multiple questions are generated when you ask for them rather than pulled from a fixed set of files, so two classes never get the same sheet, and the answer key comes with it.

Yes. There are two levels, and you can tick more than one for a sheet that mixes them, in which case the questions come out easiest first. The harder levels are not just larger numbers: they ask for something the easy ones do not.

Multiplying the two numbers together. That always gives a common multiple, but it is only the least one when the two share no factors; 6 times 8 is 48, and 24 gets there first.