How many 3 digit counting numbers less than 800 have digits that are all even?

1 Answer
Dec 2, 2016

75

Explanation:

Considering the possible values of each digit in turn:

First digit #{2, 4, 6}# Since the number #< 800# (Assuming a leading 0 is not allowed) = 3 possibles

Second digit #{0, 2, 4, 6, 8}# = 5 possibles

Third digit #{0, 2, 4, 6, 8}# = 5 possibles

Hence the number of 3 digit numbers #in NN < 800 # where all digits are even is:

#3xx5xx5= 75#