How many three-dight integers greater than 600 contain only odd digits?
the first digits greater then 600 has to be 7xx, or 9xx
the second digit, and the third can be 1,3,5,7,9 or five possibilities.
So how many? 2 x 5 x 5 or fifty.
the second digit, and the third can be 1,3,5,7,9 or five possibilities.
So how many? 2 x 5 x 5 or fifty.