Rounding decimals

[Preciouzgeek]

Ok, so I was doing decimal calculations in some of my practice problems. In order to practice efficient rounding techniques, I've developed a habit in rounding to the nearest whole number (i.e. if specific heat = 4.184, I'll round to 4).

But I've encountered a handful of practice problems that ask to round to the nearest decimal -- because the answers were very similar.

So what are some of the the general rules to rounding/approximations on the MCAT? (I.e. Should we always round to the nearest decimal if decimals are involved, or don't round until the absolute end etc.)

---

Members don't see this ad.

 

[MT Headed]

I usually try to answer the question myself, and then look to see what answer that matches. However, in the case of a numeric calculation type question, which is uncommon on the mcat, it pays to look at the answer choices first.

If you see something like: 2, 20, 200, 2000 you know you can be cavalier about rounding and be very careful about the exponent in scientific notation. Watch for a kilometer when you expected meter, etc.

If you see something like 1.95, 1.97, 2.00, 2.03, you know you need to be more careful. Or (hopefully) you can quickly prove that the answer is more than 2 and you saved yourself a ton of time.

The worst possible outcome is you spend a lot of time on calculations, solving something like (30)(256)/(18)(9.2) to get 46ish, and the answers all look like:
a: (30)/(18)(256)(9.2)
b: (256)(18)(30)/(9.2)
c: (30)(256)/(18)(9.2)
Now that's a real DUH feeling!

If I have to round, I will usually round enough to make the problem easier to solve. Taking genuine aamc practice tests will give you a better feel for how much to round on the mcat. Study guides usually have a lot more math than the real thing.

 

[Preciouzgeek]

That helped, thanks