Find the GCF of 18 and 40.

To find the greatest common factor (GCF) of 18 and 40, we can use different methods such as prime factorization, listing factors, or using the Euclidean algorithm. Here is one method:

First, we can list the factors of both numbers:

Factors of 18: 1, 2, 3, 6, 9, 18 Factors of 40: 1, 2, 4, 5, 8, 10, 20, 40

Then, we can identify the common factors of both numbers, which are 1 and 2.

However, we need to find the greatest common factor, which is the largest number that divides both 18 and 40 without leaving a remainder. To do this, we can continue dividing the larger number by the smaller number until we get a remainder of 0. The last divisor before we get a remainder of 0 is the GCF.

Using this method, we can start by dividing 40 by 18:

40 ÷ 18 = 2 with a remainder of 4

Then, we can divide 18 by 4 (which is the remainder from the previous step):

18 ÷ 4 = 4 with no remainder

Therefore, the GCF of 18 and 40 is 4.