Question

Dear Mitch,

I know this is all people are asking for now, but could you keep giving last-minute tricks for the SAT this Saturday?

Thank you,

Evan C.

Answer

Dear Evan,

Of course!

My only concern is that if you end up with a huge collection of these 'last-minute' tips, it could defeat the purpose – after all, these short tips are popular because they're easy to remember and easy to apply, but if you have a list of two hundred of them, then you're basically back to where you probably don't want to be, which is this:

Having to memorize a whole book-load of information!

Anyway, here's something that can help you catch shortcuts and avoid messing up easy questions that you know you should get right:

While most students who have studied even a little for the math section of the SAT exam probably realize that unit-changes account for a shockingly high number of double-takes when working out the word problems, there is a flip-side to the situation that can actually *help *you.

First, though, a reminder about the unit-change obsession that the authors of the test seem to have almost every year: They'll ask a question in inches and give the choices in *feet*, or ask the question in pounds and give the choices in *ounces*, or ask the question in feet and give the choices in *yards*, or ask the question in dollars and give the choices in *cents*, etc.

O.K. Now, LISTEN: There is NO law saying that the people who make the test are the only ones allowed to change units. In other words, if an exam question shows a floor plan for a rectangular room, and it is accompanied by a description such as:

"6 feet by 39 feet,"

You might take a moment to see if any magic occurs when you take your pencil and lightly cross off those numbers and units and replace them with something like this:

2 YARDS by 13 YARDS.

Why? Well, for one thing it is suspiciously convenient that the number of feet in both of the initial measurements are easily divisible by 3, which of course is one yard.

Secondly, after you try this unit change, you should glance down at the choices to see how they are presented. If you are being asked what the area of the floor is, and the choices are surprisingly small numbers, then within another moment you'll probably notice that they have switched to larger units. (Just as 200 cents is only 2 dollars, because a dollar is a larger unit than a cent...) So, if you see "26 square yards" as one of the choices, not only will you know that that is correct, but think what a waste of time it would have been to calculate with the numbers of feet they gave you:

(39 x 6 = 234 square feet), and then...

you would have to divide 234 by 9, because a square yard is one yard by one yard, or 3 feet by 3 feet, which is 9 square feet...

And you would get.... 234/9 = 26.

BUT, that was done with a lot more work than the previous way, when you took it upon yourself to change units. AND, these were small, easy numbers. What if they were huge numbers?

I think this approach can save you time and help you rack up points.

Lastly, this unit-change idea is related to something I detailed a few days ago in response to another student's question:

ON THE SAT EXAM...

THE NUMBERS ARE CHOSEN FOR A REASON!!

Hope this helps,

Good luck on your big day,

Mitch