The top number always denotes the number of beats in a measure, and the bottom always signifies what note gets the beat. If the bottom number is an 8, then you should count eighth notes. If the bottom number is a 2, then you should count half notes.
How do you count beats in music?
The top number tells you how many beats will be in each measure. The bottom number tells you what kind of note each beat is. For instance, if the bottom number is 1, that means whole notes and if the bottom number is 2, that means half notes. Similarly, 4 means quarter notes and 8 means eighth notes.