Cases of word usage

1) the academic subjects, areas of study, in which imagination and personal appreciation are more important than exact measurement and calculation (arts)

2) an approximate calculation (of size, cost etc) (estimate)

3) to form an opinion, give an answer, make a statement about (something) that is not based on very careful thought, calculation or definite knowledge (guess)

4) academic subjects, areas of study, in which exact measurement, observation and calculation are used (science)