1. there are three numbers less than four (1,2, and 3) on a 6-sided number cube.
2. there would be 3/6 (three possible numbers less than four out out six total possible numbers) chance that you would roll a number less than 4.
3. 3/6 simplified is 1/2 or 50%
4. so there would be a 50% chance that you could roll a number less than 4