|
[an error occurred while processing this directive]
|
Daily
Brain Teaser / Puzzle
October 20, 2009
Follow
us on FACEBOOK
or TWITTER
Previous
Days Teaser -- Want More? --Next
How many 5-digit numbers are there that do not contain the numbers 3 and 5, and are multiples of 4?
(It cannot start with 0, ie. 01234 is not a 5 digit number)
VIEW
SOLUTION BELOW
THE
SOLUTION
9408
The rule of divisibility says that a number is a multiple of 4 if its last 2 numbers are multiples of 4. So the last 2 numbers can be 21 different options:00, 04, 08, 12, 16, 20, 24, 28, 40, 44, 48, 60, 64, 68, 72, 76, 80, 84, 88, 92, 96 because they are multiples of 4 and do not have 3's or 5's.
We have the last 2 digits we need to know how many can be in the first digit: 1, 2, 4, 6, 7, 8, 9 and the second and third numbers can have these 7 and number 0 too.
|
