## Problem: The common factor of 20 and 24 is

a.1,2,3,4,5,6

b.1,2,4

c.2.4

d.2

The common divisor of 20 and 24 is **1, 2, and 4**.

Answer: B

**DISCUSSION**

*○* Least Common Multiple (KPK).

LCM of 2 or more numbers is a number that is a multiple of 2 or more numbers.

So, the LCM of 2 or more numbers is an integer with a positive value and can be divided by 2 or more numbers.

**How to find the LCM value**

There are 2 ways to find the value of the LCM, namely

For example, to find the LCM between 14 and 4, a simple way to find the LCM is…

Multiple:

14 = 14, **28** , 42, 56, 70, …

4 = 4, 8, 12, 16, 20, 24, **28**, …

The LCM of 14 and 4 are equal and smaller multiples, so the LCM is **28**.

Method This uses a factorial tree.

For example, by finding the LCM of 8 and 12, a factor tree is created:

So:

8 = 2³

12 =

2² x 3 The LCM of 8 and 12 is 2³ x 3 = **24**.

.

**FPB**

*The greatest common divisor* or abbreviated as GCD is known as the great common divisor (GCD).

The GCF of 2 or more numbers, i.e. the integer with the largest positive value and also divisible by both (or more) of these numbers.

**How to find the GCF value**

There are 2 ways to find the GCF value, namely:

For example, to find GCF 14 and 4, a simple way to find GCF is:

Factor 14 = 1, **2**, 7, 14

Factor 4 = 1, **2** , 4

The GCF of 14 and 4 is **2**. These numbers are the same and greater factor.

Factorial method The factorial method uses a factorial tree.

For example, by finding the PGCF of 8 and 12, a factor tree is created:

So, prime factorization:

8 = 2³

12 = 2² × 3

PGCF of 8 and 12 = 2² = **4**.

○●○●○●○●○●○●○●○●○●○●○●○●○●○●○●○

After listening to the short explanation above, let's solve the problem.

**Known:**

20 and 24

**Wanted:**

Find the common factor…!

**Answer:**

To find the common divisor of 20 and 24, find the divisor that is a number that is divisible by 20 and 24 (eg 20:2, 20:4, etc.), namely:

20 = **1**, **2**, **4**, 5, 10, 20

24 = **1**, **2**, 3, **4**, 6, 8, 12, 24

Among the factors above, the common factor of 20 and 24 is taken. So, the common factor of 20 and 24 is . . .

.

**CONCLUSION**

So, the common divisor of 20 and 24 is **1, 2 and 4**.