1. a bicycle lock has 4 rotating cylinders, each contains 10 digits. How many numerical codes are possible?
2. there are 11 positions on a soccer field . If 11 people show up to play, how many ways are there to arrange them on the field?
3. how many different license plates can be made if each license plate contains four digits and two letters? Digits may be used more than once, but the letters may not. ​
