What does LCM mean in mathematics?

The least common multiple or LCM of two numbers 8 and 20 is defined as the smallest positive integer which is divisible by both of them. It is represented by LCM(8, 20).

Properties of LCM

  • The LCM of two given numbers is never less than any of those numbers. Eg- LCM of 8 and 20 is 40, where 8 and 20 are less than 40.
  • LCM is associative which means LCM(8, 20) = LCM(20, 8).
  • LCM is commutative which means LCM(a, b, c) = LCM(LCM(a, b), c) = LCM(a, LCM(b, c)).
  • LCM is distributive, which means LCM(ab, bc, ad) = d * LCM(x, y, z).
  • The LCM of two or more prime numbers is their product.

Steps to find lcm of 8 and 20 by Listing Method

Example: Find lcm of 8 and 20 by Listing Method

  • Multiples of 8: 8, 16, 24, 32, 40, 48, 56, 64, 72, 80, 88, 96, 104, 112, 120, 128, 136, 144, 152, 160
  • Multiples of 20: 20, 40, 60, 80, 100, 120, 140, 160

Hence, LCM of 8 and 20 is 40.

Steps to find LCM of 8 and 20 by Common Division Method

Example: Find lcm of 8 and 20 by Common Division Method

2 8 20
2 4 10
2 2 5
5 1 5
1 1

Hence, LCM of 8 and 20 is 2 x 2 x 2 x 5 = 40.

Steps to find lcm of 8 and 20 by Formula

Example: Find lcm of 8 and 20 by Formula

  • GCF of 8 and 20 = 4
  • LCM of 8 and 20 = (8 x 20) / 4
  • => 160 / 4

Hence, LCM of 8 and 20 is 40.

Examples

Franky and Joy are running on a circular track. They start at the same time. They take 8 and 20 minutes respectively to go round once. Find at what time they will run together?

Franky and Joy are running on a circular track. They take 8 and 20 minutes respectively to go round once. We need to find out at what time (minimum) they will run together again. For this we need to find the LCM of 8 and 20.
So, LCM of 8 and 20 is 40.

A shopkeeper sells candies in packet of 8 and chocolates in packet of 20. What is the least number of candies and chocolates Annie should buy so that there will be one candy for each chocolate?

The least number of candies and chocolates Annie should buy so that there will be one candy for each chocolate we need to find the lcm of 8 and 20.
So, LCM of 8 and 20 is 40.

Both the cricket team and the rugby team had games, today. The cricket team plays every 8 days and the basketball team plays every 20 days. When will both teams have games on the same day again?

Given that the cricket team plays every 8 days and the basketball team plays every 20 days, so for finding the next time when both teams will play again we need to find the LCM of 8 and 20.
So, LCM of 8 and 20 is 40.

Sammy's company prints 8 textbooks at a time. Daniel's company prints textbooks in sets of 20 at a time. According to a survey done by a committee, both companies printed the same number of textbooks last year. Find the least number of books that each company would have printed.

To find the least number of textbooks that each company could have printed we need to find the LCM of 8 and 20.
So, LCM of 8 and 20 is 40.

Ariel exercises every 8 days and Rubel every 20 days. They both excercised today. How many days will it be until they excercise together again?

The problem can be solved using LCM, because we are trying to figure out the least time until they excercise together again.
So, LCM of 8 and 20 is 40.

What is the relation between LCM and GCF( Greatest Common Factor)?

Greatest common factors or gcf of 8 and 20 is GCF(8, 20) * LCM(8, 20) = (8 x 20) / GCF(8, 20) = 40.

Find the least number which is exactly divisible by 8 and 20.

Least number which is exactly divisible by 8 and 20 is 40.