Question

Sally has 6 red​ flags, 5 green​ flags, and 4 white flags. How many 15​-flag signals can she run up a flag​ pole?

Answer 1

There are ten spots where you can put a white flag. 10  

There are nine spots where you can put a second white flag. 9  

There are eight spots where you can put a green flag. 8  

Likewise --- 7  

Likewise --- 6  

There is only one way to fill the remaining spots with red flags.  

Total: 10 x 9 x 8 x 7 x 6 = 30,240