As you are preparing for your Armed Services Vocational Aptitude Battery or ASVAB exam, you will be asked to perform calculations that require you to divide large numbers not for the purpose of seeing what the answer is, but to see if the number is divisible by such number. In this article I will give you the divisibility rules for the numbers 1 through 3.
Since you are not allowed to use a calculator on the ASVAB, this can potentially take a long time
Divisibility Rule For #1
Any number can be divided by number 1 giving you the original value. You will likely never even be asked such a question.
Divisibility Rule For #2
Since number 2 is an even number, if you are asked to divide any number by 2 and the number is even, then this number by definition is divisible by 2.
Divisibility Rule For #3
3 is one of those tricky numbers. Sometimes It may be difficult to identify an exact trick when you’re looking at a ridiculously long number. However, there is one rather crafty trick that you can apply that will save you the long, drawn out pen and paper calculation to find out if large numbers are divisible by 3.
The way you see if a number is divisible by 3 is by taking that number, breaking up the digits and then adding all the digits to each other. If the digits add up to a number that is divisible by 3, then the entire number is also divisible by 3. If the digits add up to a number that has more than two digits, go ahead and add them up again.
Let’s look at a quick example. Say I asked you to divide the number 897,543 by 3. How can you know if it’s divisible? Well you can do the long, drawn out pen and paper calculation or you can simply add the digits. You will add 8 + 9 + 7 + 5 + 4 + 3. This will give you a total of 36. And while this may appear tedious, it is significantly faster than doing long division
Thirty-six has two digits. So once again, we will apply this trick and add the digits 3 + 6 and this gives me 9. Since 9 is divisible by 3, that means the entire number is divisible by 3 and it took me all of a few seconds to figure out.
