How to express the inner diameter of the bearing?

The face of the bearing inner ring on the periphery or the number seen right from the first and second digit is the inner diameter of the bearing, i.e. with the diameter of the shaft. Press the bearing bore size divided into the following methods:
1, codenamed digital since 04 till 99 only, each pair of numbers from right to come ride with five figures represent the two high precision bearings bore size. For example, two digits after the 204 bearing 04, an inner diameter of 04 × 5 = 20 (mm). This section numbers bearing is the most common, it represents the bearing diameter from 20 mm to 495 mm.
2, the inner diameter of 10 to 20 mm in all the bearings (except magneto bearing), which diameter is constant, expressed as follows:
3,1-9 mm (including 9 mm) of small bearings, has its special representation:
Right from the first digit indicates the actual size of the bearing bore,
Right from the second digit indicates the bearing diameter series;
Right from the third digit is O.
For example: There is a small 25 bearings - right from the first digit "5" indicates the bearing inner diameter of 5 mm, the second digit "2" indicates that the bearing is light series single row radial ball bearings, the third digit is " 0 "did not write. Another example: 1006 self aligning roller bearings, represents an inner diameter of 6 mm light series double row spherical ball bearings.
Magneto ball bearings from the right two digits represent the actual size of the inner diameter. As 6015 bearing, represents an inner diameter of 15 mm of magneto ball bearings.
4, bearing diameter is not an integer, is part of a non-standard bearings. In this case, said in an approximation bearing code, and the third from the right in the figures marked with the number 9. Such as the Beijing brand BJ212-road automobile clutch release bearings 688,911, the actual size of the bearing inner diameter = 52.388 mm, diameter = 84.5 mm, width = 20.7 mm. 688911 bearing from the right of the first, two numbers are 11, according to the provisions of its diameter size should be 11 × 5 = 55 mm, but the actual size of the spherical ball bearings

 inner diameter of 52.388 mm. So it takes approximately 55 mm for digital proud bearing diameter code.
5, bearing code figures represented by the following three points:
(1) Bearing in 500 mm diameter size to LIi, the denominator figure represents the actual size of the inner diameter of the molecule digital representation of its series, the type and structure of the method according to the general bearing and regulations. For example 71/900 bearing denominator digital representation of the bearing inner diameter of 900 mm, molecular digital representation for the special lightweight single row tapered roller bearings.
(2) Needle roller bearings do with fractional code, the denominator figure represents the inner diameter of the bearing. For example 943/25 bearing denominator represents the inner diameter of the bearing 25 is of 25 mm.
(3) When the miniature bearings do with fractional code, its denominator figures represent the actual size of the inner diameter of the bearing. Such as 1009 / 2.5) bearing the denominator 2.5, is the diameter of the bearing is 2.5 mm.