Sentence:  The points to <WSD>nick</WSD> each main have been mentioned before, and the table on dice will show how many chances there are to throw each of these points with 2 dice, which together form the numerator, and 36 (being all the chances on 2 dice) the denominator of the fraction that expresses the probability. If 5 is the main, 5 will be the only nick, and the chances to throw 5 being 4, frac 
Meaning of the word marked with <WSD> tags:  To throw or turn up (a number when playing dice); to hit upon.