Which number is less than 28.43 is it 28.435 or is it 28.34 or is it 28.430 or is it 29.43?

The number that is less than 28.43 is 28.34. The other options, 28.435, 28.430, and 29.43, are all greater than or equal to 28.43. Therefore, 28.34 is the only number that meets the criteria.