I don't understand why the answer is 9. The problem goes:

When two digit integer q is divided by 9, the remainder is 4, if q is a multiple of 7. Which of the following could be the units of q?


0?1?5?7? or 9?

The answer is 9. I dont get the table!

The chart can be a little confusing at first, until you see what they're doing.

Here's the thinking.

We know that the number we're after is 4 more than a multiple of 9.

The 2-digit multiples of 9 are

18, 27, 36, 45, 54, 63, 72, 81, 90, 99
The numbers that are 4 more than those are
22, 31, 40, 49, 58, 67, 76, 85, 94, 103

Then, we look at these to see which one is also a multiple of 7.
The one that works is 49.

The units digit of 49 is 9, so this is our answer.

Hope this helps!

Veritas Help

So you’re saying since the multiple of 9 is: 27,36, and 45. And there is a remainder of 4. At the same time, we have to consider the multiple of 7, that goes: 21,28,35, 49.

And since we have the multiple of 9 equals to 45 + the remainder of 4= 49, and the multiple of 7 = to 49. We take the second digit of 9 from the 49 because of the 2 digit of multiples?

So if we are saying: 2 digit of multiples of 3 with remainder of 3 and has a multiple 4. The answer would be 4? bc 21+3 = 24, and the multiple of 4 = 24. So we take the 4. Similar to the question you answered?

Can any Veritas representative reply to my post!?

Hey LT,

I think you're right - just to clarify, are you using the term "2 digit" to mean "the second digit"? The initial question asks about the units digit, and it's a 2 digit number so technically it's the "second digit", but be careful...as you'll see in the Arithmetic lesson the GMAT does explicitly test the units digit concept, so you'll certainly want to get familiar with that terminology as you'll almost certainly see it on test day.

Your hypothetical is absolutely correct, so it sounds like you've gotten the concept perfectly - I'd just urge you to work on the terminology so that you're able to replicate the process as it's asked by the GMAT.