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SAT Math: Arithmetic

Digits

X and Y are distinct integers less than 6.  Given the correctly worked addition problem below, which of the following could be equal to XY?

Screen Shot 2013-12-10 at 4.52.26 PM.jpg

A. 26
B. 33
C. 35
D. 42
E. 44

Knowsys Method

Read the problem carefully.  A very important word to note in this problem is “distinct.”  If x and y are distinct, they cannot be the same number.  That eliminates answers B and E already.  Also, notice that X and Y must be less than 6.  That eliminates A.

Identify the bottom line.  XY = ?

Assess your options.  You can either plug in the answers or think about the problem logically.  The latter method is quicker, so we will demonstrate that below.  

Attack the problem.  If you look at the addition problem, you will see that X and Y must add up to 8.  The numbers in choice A add up to 8, but we already eliminated choice A in step 1.  That leaves us with choice C.  3 and 5 add up to 8, and if you sub in 3 as X and 5 as Y, you get this:

Screen Shot 2013-12-10 at 4.22.48 PM.jpg

Loop back.  Did you solve for the bottom line?  Yes.

The correct answer is C
This is an easy level problem

Want some help reviewing the math concepts you need to master?  Try out the Knowsys Pre-Algebra Flashcards, the Knowsys Algebra I Flashcards, and the Knowsys SAT & ACT Math Practice book.  

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