of the 3 - digit integers greater than 700 , how many have distinct digits ?
Choose one:
A) 216
B) 82
C) 80
D) 45
E) 36

Rationale: three digit number can have only following 3 patterns : a . all digits are distinct ; b . two digits are alike and third is different ; c . all three digits are alike . we need to calculate b . b = total - a - c total numbers from 700 to 999 = 299 ( 3 - digit numbers greater than 700 ) ; a . all digits are distinct = 3 * 9 * 8 = 216 answer : a
Answer: A