Problem
COM-B1-M02-P015 Four-Digit Multiples of \(5\)
#15
★★★☆☆ Level 3 of 5
How many four-digit numbers with distinct digits can be formed from \(0,1,\ldots,6\) if the number is divisible by \(5\)?
The last digit is \(0\) or \(5\).
If the last digit is \(0\), the first digit has \(6\) choices, then \(5\) and \(4\): \(120\). If the last digit is \(5\), the first digit is not \(0\) or \(5\): \(5\) choices, then \(5\) and \(4\): \(100\). Total: \(220\).
Revisits the important zero trap.