In my view, the "slot method" is meant to be used when there are no repeating items. It's not meant to be a catch-all approach for every permutations question.
It works fine for most simple permutations questions because most simple questions don't have repeated elements. Luckily, this covers most GMAT permutations questions.
The slot method cannot work for situations when there are repeated elements, because it cannot take into account things like: "Was the thing I put in the first slot one of the repeated elements, or was it not?" It is designed to be used for situations in which there is no uncertainty about any given element's availability for future slots.
It works fine for most simple permutations questions because most simple questions don't have repeated elements. Luckily, this covers most GMAT permutations questions.
The slot method cannot work for situations when there are repeated elements, because it cannot take into account things like: "Was the thing I put in the first slot one of the repeated elements, or was it not?" It is designed to be used for situations in which there is no uncertainty about any given element's availability for future slots.
Greg Michnikov, Founder of GMAT Boost
GMAT Boost offers 250+ challenging GMAT Math practice questions, each with a thorough video explanation, and 100+ GMAT Math video tips, each 90 seconds or less.
It's a total of 20+ hours of expert instruction for an introductory price of just $10.
View sample questions and tips without signing up, or sign up now for full access.
Also, check out the most useful GMAT Math blog on the internet here.
GMAT Boost offers 250+ challenging GMAT Math practice questions, each with a thorough video explanation, and 100+ GMAT Math video tips, each 90 seconds or less.
It's a total of 20+ hours of expert instruction for an introductory price of just $10.
View sample questions and tips without signing up, or sign up now for full access.
Also, check out the most useful GMAT Math blog on the internet here.
