SAT Question of the Day (ACT too!): Mar. 20, 2014

If you are reading this in an email you received from me, do not click the link to below. Use the link to my website that is farther down on the email. (This link takes you to today’s question. If you use my archive, you will see the question related to my SAT explanation for that date.)

Less than half of the students (41%) are getting this question correct right now.  That makes it moderately difficult meaning most students are missing it.  But why?  It is only about multiplying numbers and their factors.  If they were following my blog, they’d have a much easier time of it.  Follow along.

The answer is E.  No calculator involved!  All the multiples of 7 are 7, 14, 21, 28, etc. and multiples of 13 are 13, 26, 39, etc.  They will have a common multiple (a multiple they share or have in common) the first time at 7 x 13 = 91.  Then at 2 x 91, they will have a common multiple.  Then at 3 x 91 and 4 x 91 so on, they will intersect again and again.  That means there’s an infinite number of common multiples.  (“Common multiples” is a term that is used on the ACT from time to time and you need to understand it.  It just means multiples that are in common for two or more different integers.)

Did you have trouble with this question?  If so, it is probably because they used awkward numbers like 7 and 13 with a product of 91.  When you see problems that are confusing to think about due to the numbers you are given, be sure to remember my mantra: “The world of math is a world of patterns.”  You could pick any two numbers and check to see how they would work.  I recommend avoiding 1 when you do this because sometimes you get too many right answers!  That’s because 1 times anything will give you that number.  For example, 1 times 3 is 3.  For today’s question, if you tried to see what would happen with 2 and 3, you know right off the bat that they would have a common multiple of 6.  And since you’ve memorized the times tables (I hope), you would think about the fact that they also intersect at 12 and 18 and 24 ad infinitum.  Now you see the pattern and what’s going on.  The same pattern has to apply to 7 and 13.

I sometimes call this strategy “reduce it to the ridiculous.”  In other words, reduce or change the original numbers to ridiculously easy numbers.  See what happens with them.  The same will happen with the original numbers.  “The world of math is a world of patterns.”


I wonder if the ACT folks have something new for us this morning.

ACT Question of the Day: Use your “back” button to return to my website after reading the ACT Question of the Day.

I hope that when the new ACT comes out that they get some new QotD’s.  This one is about worn out because they keep using it over and over.  But I have lots of new members reading my blog; so, let’s take a look at it anyway.

The answer is D.  Use the “Insertable” rule of the PICK strategy which is explained on my free website and on Video #305.  When you plug in the other answers, they either add to or disagree with the passage.  D inserts just fine in the final paragraph near lines 82-85.  It doesn’t add or disagree.  Bubble it in and move on.

Research shows that students overthink the answers.  They try to justify how an answer may be correct if certain circumstances exist.  Sometimes the wrong answers are even accurate statements.  However, the foundational rule of the reading test is that the best answer must be supported by the passage and not prior knowledge or special circumstances that are not part of the passage or what “might be,” etc.  That means when an answer adds to the passage, it is wrong.  Yes, it is that simple.  Be sure you practice the technique.  You’ll find it very helpful.


We do our long-distance tutoring and college coaching via Skype.  What a terrific resource that is.  It is like sitting across the table from one another without the commuting problems and the waste of time associated with the ride.  It also allows us to work with students from anywhere and still feel like we are right there.  For example, Audrey lives over a 100 miles away and it was like she was right here last night working on her ACT score.  Max is in China and getting help with his application essays!  No problem.  (We just have to find a time when we are both awake!)  If you would like to try it, let us know.

Bob Alexander, the “SAT and ACT Wizard”


About Bob Alexander

Bob has been a professional educator starting with teaching biology, becoming a school administrator, and then working as an education lobbyist in Washington, DC. He got his start in national testing by becoming a consulting test writer, later joining Kaplan as a director, and finally starting his own business in 1995. He has written numerous books, consulted for school districts and colleges, developed his website and been featured on a DVD set. He offers SAT and ACT prep classes and tutors individuals and small groups of students in central Florida.
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