Of the six-digit positive integers that have no digits equal to zero, how many have two digits that are equal to each other and the remaining digit different from the other two? Choose one:
A) 2443200  B) 3643200  C) 5443200  D) 1443200  E) 2163200
Of the six-digit positive integers that have no digits equal to zero, how many have two digits that are equal to each other and the remaining digit different from the other two?   A. 24   B. 36   C. 72   D. 144   E. 216   Choosing the digit for p - 9 ways;   Choosing the digit for q - 8 ways;   Choosing the digit for r - 7ways;   Choosing the digit for s - 6ways;   Choosing the digit for t - 5ways;   # of permutations of 3 digits in ppqrst - 6!/2!   Total: 9*8*7*6*5*6!/2!=5443200.   Answer: 5443200.
<result>C</result>
Of the six-digit positive integers that have no digits equal to zero, how many have two digits that are equal to each other and the remaining digit different from the other two?