My old friend Owl sent me the following quote :
I realized that reading a piano piece is much like solving a math problem. Each note has a beat which is a fraction of a whole bar, and the sum of the notes’ beats in a bar should equal the numerator in the so called “time signature”, the fraction indicated on the left most side of the staff. (A staff is a series of bars.) The denominator in the time signature specifies the kind of note which would receive ONE beat. Thus, a time signature of 2/4 means that a quarter note (1/4) would have one beat, and each bar would have two beats; an eighth note (1/8) would receive a half-beat, and the bar may have as many as four eighth notes, or a combination of one quarter note and two eighth notes, and so on and so forth. Whew! Beethoven must have been a good mathematician!