when doing math on the real exam, do you write the units out?

[tdod]

I figure that the pro's/cons of writing out units in your calculation are:

• pro: prevent errors (i.e. forgetting to convert to proper units; multiplying/dividing the wrong terms)
• con: takes longer.

so, what have you found to be more effective?

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[Shirafune]

If there are lots of variables to plug in, then I'll write out the units, but if it's just F=ma or something really simple and I really only need to do a g to kg conversion then I'll just do the conversions in my head and write down the numbers only.

 

[DrknoSDN]

I agree with @Shirafune. There is rarely a reason to write down units. If you jot down a few numbers for calculations and your answer doesn't match any of the choices then you can check if you missed a basic conversion but you should try and approximate and minimize time spent writing.

I would say if your answer doesn't look like any of the option presented and you don't know what your mistake was, then make an educated guess and move on. Hopefully you could eliminate one of the choices because if your calculation came out wrong it suggests your mastery of the subject is weak and not necessarily that you mixed up the units.

 

[orangetea]

hmm.. I would actually have to say it would be wise to write out units. There have been instances on real MCATS where you have your answer in one unit but the answer choices are in another unit.

 

[sillyjoe]

hmm.. I would actually have to say it would be wise to write out units. There have been instances on real MCATS where you have your answer in one unit but the answer choices are in another unit.

It really depends on the question. Some questions I will only use units and not numbers while others I will use numbers and no units. It is much better to go through this process and develop a systematic approach to the questions not involving a global and overarching rule but rather developing conceptual approaches to each "class/type" of question and attacking it in a manner that needs the least work to get a correct answer.

I know this is usually not the answer people want to hear, but after you go through a process like SN2ed you will find that you yourself don't have "rules" that you use to attack each question, you instead look at each question and think of the most effective way to answer it. For example, if you check out question #35 in TBR physics section 2 regarding the Atwood Machine. Even though this isn't a unit question I think it gets across my point well. When I first looked at that question I felt like this:

But when I really took a look at it I saw I could cancel out choices first by using units and then by using extreme cases. What I am trying to point out is that it is much more effective to develop conceptual test taking strategies rather than outlining global rules for you to follow.