Problem
COM-B1-M01-P013 Four-Digit Multiples of \(5\)
#13
★★★☆☆ Level 3 of 5
How many four-digit numbers with distinct digits from \(0,1,\ldots,7\) are divisible by \(5\)?
The last digit is \(0\) or \(5\); these cases differ because of the first digit.
If the last digit is \(0\), the first has \(7\) choices, then \(6\) and \(5\): \(210\). If the last digit is \(5\), the first is chosen from \(1,2,3,4,6,7\): \(6\) choices, then \(6\) and \(5\): \(180\). Total: \(390\).
Repeats the example as independent practice.