GMAT Club Legend
Joined: 07 Jul 2004
Posts: 5079
Location: Singapore
Followers: 21
Kudos [?]:
180
[0], given: 0

For hundreds digit 7 + 2 other digits
Remaining digits  11,22,33,44,55,66,88,99
Total: 8
For hundreds digit 7 + 7 in ones position
Remaining digts  17,27,37,47,57,67,87,97,07
Total: 9
For hundreds digit7 + 7 in tens position
Remaining digits  70,71,72,73,74,75,76,78,79
Total: 9
For hundreds digit 8,9 + other digits
Remaining digits: 00,11,22,33,44,55,66,77,88/99
Total: 9*2 = 18
For hundreds digit 8,9 + 8/9 in ones position
Remaining digits: 18,28,38,48,58,68,78,98,08 (19,29,39,49,59,69,79,89,09)
Total: 9*2 = 18
For hundreds digit 8,9 + 8/9 in tens position
Remaining digits: 80,81,82,83,84,85,86,87,89 (90,91,92,93,94,95,96,97,98)
Total: 9*2 = 18
Combines total = 80
