How many four-digit integers exist such that all their digits are odd? Choices: A) 80 B) 100 C) 120 D) 125 E) 625
so last digit can be filled in 5 ways- 1,3,5,7,9   there are 5 possibilities. The answer is 5∗5*5*5=625   The correct answer is 625
<result>E</result>
How many four-digit integers exist such that all their digits are odd?