Technique
Counting matrices
- the number of divisors of N
- choices available per entry
The possible orders of a matrix with a fixed number of entries correspond to the divisors of that number, and each position is then filled independently.
12
questions use it
9
of them past-year
2017–2025
years it has appeared
17%
rated HARD
3
exams
Used alongside
How often each of these appears in the same solution as this one.
12 questions whose solution uses this
Every one was read individually — a question is here because its solution invokes this, not because the stem mentions it.
Every identity this chapter tests, with its own question set.
All Matrices & Determinants formulas