Mo logo [home] [lexicon] [problems] [tests] [courses] [auxiliaries] [notes] [staff] german flag

Mathematics-Online problems:

Interactive Problem 1117: Combinations of Digits in Four-Digit Numbers


A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

How many four-digit numbers exist containing

a) one or several of the digit 0,
b) only different digits,
c) exactly two equal digits,
d) the sequence of the digits ,,1 2``?

Answer:

a)
b)
c)
d)


   

(From: Mathematics Contest 2007)

[Links]

  automatically generated: 2/ 6/2018