The number of digits doesn't have any effect on divisibility. 10000, 10004, 10008 and so on are all divisible by 4.
what is the largest three-digit number that is divisible by 4, 5, and 6
There can be no such number. If it is divisible by 5 and 6it must be divisible by 6.
44444
Any number that ends with the digit 5 is divisible by 5.Any number that ends with the digit 5 is divisible by 5.Any number that ends with the digit 5 is divisible by 5.Any number that ends with the digit 5 is divisible by 5.
4 is not divisible by any 3-digit number. Nor are 5, 11 or 3. The smallest positive numbers that is divisible by 4, 5, 11 and 3 is 660.
2000
3030
3000
5678 \
1000.
9999
4000