A multiple of 45 is any number that results from multiplying another number by 45. Therefore, 45 has an infinite number of multiples. The first three multiples of 45 are 45, 90 and 135, according to Calculator Soup. The multiple 90 results from multiplying 45 by 2.

The multiple 135 results when 45 is multiplied by 3. The next three multiples of 45, according to Calculator Soup, are 180, 225 and 270. To get 180, multiply 45 by 4. To get 225, multiply 45 by 5. To get 270, multiply 45 by 6. The two numbers multiplied together to get each result are called the factors. Therefore, 45 is a factor of each multiple.