In the addition problem above, the number \(*\) must be?

[Gmat_mission]

In the addition problem above, the number \(*\) must be?

(A) 5
(B) 6
(C) 7
(D) 8
(E) 9

Answer: B

Source: Official Guide

[Brent@GMATPrepNow]

question.JPG

In the addition problem above, the number \(*\) must be?

(A) 5
(B) 6
(C) 7
(D) 8
(E) 9

Answer: B

Source: Official Guide

STRATEGY: Upon reading any GMAT Problem Solving question, we should always ask, Can I use the answer choices to my advantage?
In this case, we can easily replace each * with each answer choice until we find the one that creates the correct addition.
Now let's give ourselves up to 20 seconds to identify a faster approach.
In this case, we can also assign variables to the missing digits, but I can already see that testing the values will be super fast.
So, let's go with that...

When we replace each * with 5, the addition doesn't work.
When we replace each * with 6, the addition works!



Answer: B