14. How many natural numbers less than 100 are there that: a) are divisible by 2 but not by 3; b) are divisible by 2 or by 3; c) are not divisible by 2 or by 3?
14. a) There are $49(98: 2=49)$ even numbers from 1 to 99. Among them, there are numbers that are divisible by 3 (such numbers are divisible by 6). There are a total of 96:6 $=16$. Therefore, the numbers divisible by 2 but not by $3,49-16=33$.

b) There are 49 numbers divisible by 2, and 33 numbers divisible by 3 (99: 3=33), and 16 numbers divisible by 6. Therefore, the numbers divisible by 2 or 3 are $49+33-16=66$.

c) The numbers not divisible by 2 or 3 are $99-66=33$.