There's an old saying that says, “Almost only counts in horseshoes and hand grenades.” In grade school and high school, you were probably taught that math had to be precise; maybe you even had that unforgivingly drilled into you. Well, now you're preparing for the Quant, and the rules are different. On Quant Math, “almost” can be good enough to count.
It's a fact that you cannot use a calculator on the Quant. Therefore, it's also a fact that the writers of the QAUNT can't expect you do long calculator-type calculations on the Quant. They can't expect you to multiply & divide ugly four-digit numbers and get an exact answer – but they can, and will, expect you to estimate.
The short answer is: whenever you would have to be a Will-Hunting-type savant to figure out the exact result in your head, that's a clue that you should ditch the exact answer altogether and try estimating. The QAUNT may give you the green light by using the words “the estimated value of” or “approximately.” Another clue is the spread of the answer choices. If the answer choices are all very close together, well, then it's going to take some precision to distinguish among them. But, if the answer choices are widely spaced, estimating will get you close enough to the right answer.
Here is an example of a question that will not appear on the QAUNT Math: “Jill invests
Here, though, is a suspiciously similar question, and one that the QAUNT could pose:
1. Jill invests
Solution: first of all, notice the magic word “approximately” — the test-writer is letting us know estimation is perfectly fine. Furthermore, the answer choices are nicely spread out, which will facilitate estimating.
OK, get ready for some fast & furious estimation. The interest rate
Notice, I estimated so that everything up until the last sum was single-digit math. Single-digit calculations are a good standard for which to strive when you are practicing estimation.
By the way, if you find the bank that will do answer (E), double your money in only two years, that's terrific, but it probably is something wildly illegal, a Ponzi scheme or worse! In the real world, that just doesn't happen. On word problems, especially in financial situations, you should always have your antenna up for what's realistic or unrealistic.
2. ACME's manufacturing costs for sets of horseshoes include a
So here's some more fast and furious estimation. Initial manufacturing outlay: round that from
Answer choice (A) is the only answer even close to that. Single digit calculations all the way, and it was enough to get the answer!
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