Directions: Using the digits 1 to 9, at most one time each, place a digit in each box so that the statement is true.
Hint
Write down the formulas for nCr and nPr and try a few guesses!
Answer
6C3 = 5P2, 6C1 = 3P2, 6C5 = 3P2
Source: Mark Alvaro and Kerri Swails
Open Middle®
At most once each?
4C2 = 6P1
9C1=9P1
You used both the 9 and the 1 twice….