larrybird wrote:Experts:
I kind of freak out every time I see a question with remainders. Can anybody give me advice of a good tutorial to read out there to understand them better ? Or maybe line out the main concepts related of to this topic that are tested on GMAT?

Thanks !!!

Can you provide an example of what freaks you out.

So for example 23/4. You know R = 3 right?

Number = (Divisor * Quotient) + Remainder

23 = (4*X) + 3

Subtract 3 from both sides

20 = 4X

X = Quotient

If you have 3 - you can the missing one.

Or are you referring to DS questions such as:

What is X equal to?

1. X/4 has a remainder of 2
2. X/6 does not have a remainder

Just pick numbers. If you can find two values - its insufficient.

So if you could pinpoint what it is you're worried about - I think we can help answer your question.

I hope I'm not derailing the OP's question, but here's an example of a remainder question that's messing me up. It's from OG, and even with their explanation, I can't understand why it's solved the way it is solved. I have a feeling I just need a lightbulb to go off, and this will go from being tough to being routine:

If s and t are positive integers such that s/t = 64.12, which of the following could be the remainder when s is divided by t?

(A) 2
(B) 4
(C) 8
(D) 20
(E) 45

Blues wrote:I hope I'm not derailing the OP's question, but here's an example of a remainder question that's messing me up. It's from OG, and even with their explanation, I can't understand why it's solved the way it is solved. I have a feeling I just need a lightbulb to go off, and this will go from being tough to being routine:

If s and t are positive integers such that s/t = 64.12, which of the following could be the remainder when s is divided by t?

(A) 2
(B) 4
(C) 8
(D) 20
(E) 45

s=64.12t
s=64t+.12t

.12t should be a whole number. for s to be a positive integer.

I read somewhere" for which of the following "questions, start from the bottom

.12t=45
t=(45/12)*100
t=375
Bingo

If you try other numbers, they will not work.
Hope this helps

A variation of this question I just thought ...

If s and t are positive integers such that s/t = 64.17, which of the following could be the remainder when s is divided by t?

(A) 8
(B) 13
(C) 39
(D) 234
(E) 472

Is there any correct answer for this (among the choices0?

If the remainder is divided by the divisor (t), the result (quotient) is 0.17 (I will assume it is not the rounded-off/truncated value).

Hence, if we divide the remainder by the quotient from above (0.17, which is now the divisor), the divisor from above, t, becomes the quotient. But, t is an integer.

Now, try dividing each of the below options by 0.17 such that you get an integer, which will be t. There should be only one such value. When you try with 0.17, you don't get any integer results for the set of remainders in the answer choices. So, I think you probably tweaked the problem for learning purpose. But, I guess you have gotten the idea of how to tackle such problems.