#894 · Combinatorics · Counting

Flag signalling

Four flags of different colours can be hoisted one above another, any number of them (including none) may be hoisted at once. How many different signals are possible? Repeat for five flags.

~2 minAnswer checked instantlysubsetspermutations

H. S. Hall & S. R. Knight, Higher Algebra (1891) · Ch. XI. Permutations and Combinations, Examples XI.b, No. 22

Stuck? A gentle nudge

Something off?

Workspace

Your answer

Loading the math keyboard…

Type naturally — sqrt, pi, / and ^ become notation. Any equivalent form is accepted. Press Enter to check.