It is important for musicians to understand that any musical note can be expressed by a 'Ratio' using numbers. For eg.,

S (say,100 Hz) is expressed by 1/1, because, 100 X 1/1 = 100
P (150 Hz) is expressed by 3/2, because, 100 x 3/2 = 150
G (125 Hz) is expressed by 5/4, because, 100 x 5/4 = 125
S' (200 Hz) is expressed by 2/1, because, 100 x 2/1 = 200
M (133.33 Hz) is expressed by 4/3, because, 100 x 4/3 =133.33

Such a ratio which expresses any 'number' has tremendous practical value as it can accurately show the 'point' on a string where that 'note' is accurately played.

For example, 'Madhyam' has a ratio of '4/3' and it can be played at '3/4' or '75' % length of any string. (See Topic 33)