The denominator, or bottom number, in the fractional frame rate. For example, if your frame rate is 24000 / 1001 (23.976 frames per second), then the denominator would be 1001.
The numerator, or top number, in the fractional frame rate. For example, if your frame rate is 24000 / 1001 (23.976 frames per second), then the numerator would be 24000.