Knowing some GMAT tricks will help you save time and improve your chances of doing well on the GMAT. In this video, we’ll show you a few 3 digit odd number tricks that will help you Ace the GMAT Test.
GMAT 3 Digit Odd Number Tricks [Transcipt]
In this question, we must use the following digits to create three digit odd numbers. So as always, let’s begin by listing some possible outcomes. They include 685, 241, 815, and so on. Now can we pick the task of building these three digit numbers and break it into stages. The answer is yes. We can let one stage be selecting the first digit, another stage can be selecting the second digit, and another stage can be selecting the third digit.
Now when we break a task into stages, we should always begin with the most restrictive stage. In this question, the most restrictive stage is selecting the third digit. This stage is the most restrictive since our three digit numbers must be odd, which means out third digit must be wither one or five.
So there are two ways in which we can accomplish this stage. Now once we’ve completed this stage, we should recognize that the two remaining stages are equally restrictive, so it doesn’t matter which stage we tackle next.
So let’s select the first digit. In how many ways can we accomplish this stage? Well, keep in mind that our three digit number cannot contain any repeated digits. So since we’ve already used one of the digits to accomplish the third stage, only five digits remain. So there are five ways in which we can select our first digit.
At this point, we’ve used up two of our digits, so only four remain. So there are four ways in which we can select the second digit.
Now that we’ve determined the number of ways to accomplish each stage, we can apply the fundamental counting principal, and find the product of these stages to get 40. So we can create 40 three-digit odd numbers using the given digits. So our answer here is A.