FoundationMultiple choice
A four-digit PIN allows repeated digits. How many are there?
- A
- B, choosing four digits from ten
- C ordered picks
- D, choosing a position for each digit
The worked solution is in Premium
The answer, the full working and the one idea to take away – for this and all 1,322 questions in the bank. Answer it in practice and your working is marked, with a known mistake named when you make one.
Learn the method
Reported in interviews at
More counting and combinatorics questions
- How many ways can a committee of 3 be chosen from 8 people?Foundation
- Five people sit in a row.Foundation
- What is the smallest group of people that guarantees at least three share a birth month?Foundation
- Six people sit at a round table.Foundation
- How many distinct arrangements are there of the letters of MISSISSIPPI?Foundation
- How many solutions are there to x₁+x₂+x₃ = 10 in positive integers?Foundation