Properties of Zero

[aditikedia]

Is zero considered a positive even number on the gmat?

[VP_Tatiana]

Zero is considered an even integer. However, there are 3 distinct classes of integers: positive, negative, and 0. 0 is not positive.

Tatiana

[lightbulb]

I was at a Kaplan test center today to take the diagnostic test.

One of the questions (Math # 13), led me to list numbers such that:
- The number x is prime
- The number x < 15
- The quantity (x -2) is a multiple of 5

So, I got the set of prime numbers: x: {2,3,5,7,11 and 13}
The set of numbers such that (x - 2) is a multiple of 5: {7}

BUT:
According to their explanation, x = 2 is also correct, since according to them 0 is also a multiple of 5. I understand that when zero is divided by any number (other than 0), you get zero. But I am not sure if you can call zero a multiple of every number and I am wondering what GMAC's/GMAT Instructor's thought's are about this.

Here is the link to their explanation (Math, #:13)

https://www.kaptest.com/oneoff/testdrive ... ations.pdf

[Ian Stewart]

BUT:
According to their explanation, x = 2 is also correct, since according to them 0 is also a multiple of 5. I understand that when zero is divided by any number (other than 0), you get zero. But I am not sure if you can call zero a multiple of every number and I am wondering what GMAC's/GMAT Instructor's thought's are about this.

GMAC's definition of 'multiple' will be the same as that used universally in mathematics. What does it mean for 'x to be a multiple of y'? It means you can multiply y by an integer to get x. The multiples of 5 are:

...(-2)*5, (-1)*5, (0)*5, (1)*5, (2)*5, ...

i.e.

...-10, -5, 0, 5, 10, ...

In brief, zero is a multiple of every integer (and even of zero).

[lightbulb]

Thanks for your response.