Find the smallest positive multiple of 21 that has no digit smaller than \(5\).
+2666 Let's count the multiples of 21 that are less than 100: 21, 42, 63, 84
The next possible range is \(>550\), (because anything less always has a digit less than 5 in the hundreds or tens place):
The multiples are: 567, 588, 609...
We can see that the smallest number with no digit less than 5 that is divisible by 21 is \(\color {red}567\)
