Directions: Using the digits 1 through 9, once each, fill in the blanks 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

At most once each?

4C2 = 6P1