The smallest three-digit number exactly divisible by 4 is 100.
According to the reference provided, the smallest three-digit number that is divisible by 4 is indeed 100. This is because:
- The smallest three-digit number is 100.
- A number is divisible by 4 if the number formed by its last two digits is divisible by 4.
- The last two digits of 100 are '00', which is divisible by 4.
Therefore, 100 meets the criteria of being the smallest three-digit number and being divisible by 4.
