[GMAT math practice question]
How many 5 digit numbers have at least one zero digit?
A. 30951
B. 40141
C. 47132
D. 50001
E. 50433
=>
The number of 5 digit numbers is 99999 – 10000 + 1 = 90000.
The number of 5 digit numbers which have no 0 digit is 9 * 9 * 9 * 9 * 9 = 59049.
When we encounter the words “at least” in probability questions, we should consider the complementary case and subtract the number of ways it occurs from the total number of possibilities.
...
How many 5 digit numbers have at least one zero digit?
A. 30951
B. 40141
C. 47132
D. 50001
E. 50433
=>
The number of 5 digit numbers is 99999 – 10000 + 1 = 90000.
The number of 5 digit numbers which have no 0 digit is 9 * 9 * 9 * 9 * 9 = 59049.
When we encounter the words “at least” in probability questions, we should consider the complementary case and subtract the number of ways it occurs from the total number of possibilities.
...
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