Random Number Between 1 and 8
Eight outcomes, each with a 12.5 percent chance. Eight is a power of two, which makes this the one small range you can reproduce exactly with coins rather than dice.
1 to 8 1
8 possible values, each equally likely. Tick nothing and repeats can happen; that is what random means.
Each number is 12.5 percent
Eight equally likely outcomes means 1 in 8 for every value, which is exactly 12.5 percent. That is a rare tidy figure. Most ranges give a repeating decimal; this one does not, because 8 divides cleanly into 100 eighths of a percent.
Three coins give this range exactly
Because 8 is 2 x 2 x 2, three coin flips produce eight equally likely patterns and each pattern maps to one number with nothing left over. Read heads as 1 and tails as 0, treat the three flips as a binary number from 0 to 7, then add one. No rerolling, no discarded outcomes. Compare that with 1 to 6, where six does not divide into eight and you have to throw some patterns away. If you want the flips themselves, use flip a coin 3 times.
Repeats come sooner than people expect
Two draws in a row match 12.5 percent of the time. By the fourth draw the chance that something has repeated is already 58.98 percent, so more often than not four draws will not give you four different numbers. Seeing all eight values takes about 21.7 draws on average. If you need eight different results, draw from a list instead with the random picker, which can take names out as they are chosen.
Common uses
- Lane, seat or table assignment for eight
- Bracket seeding in an eight-player draw
- Standing in for an eight-sided die: see roll a d8