What is the greatest positive integer R such that 3^R is a factor of 9^10? Pick:
A) R=5 B) R=9 C) R=10 D) R=20 E) 30
What is the greatest positive integer R such that 3^R is a factor of 9^10?   9^10 = (3^2)^10 = 3^20   D. 20
<result>D</result>
What is the greatest positive integer R such that 3^R is a factor of 9^10?