Page:The Whetstone of Witte.djvu/47

 equalle to the greater side, and the diameter added together: therfore seyng. 25. added to. 24. maketh. 49. that. 25. must nedes bee the diameter to the foresaied nomber.

By these rules (if you doe marke them well) you maie sone perceiue, how to make any diametralle nomber: if the lesser side bee giuen vnto you, and bee an odde nomber. Yet for your ease, I will giue you this plaine rule.

When any odde nomber is propounded: as the lesser side of a diametralle nomber, and you would finde the other side, and the diameter also: or els the diametralle nomber, that maie haue soche a side: multiplie that proponed nomber by it selfe, and it will make a square nomber, and will be an odde nomber: so that of it you shall finde no iuste halfe. Therfore take you those twoo nombers, that are nexte vnto the halfe of it: The lesser shall alwaies bee an euen nomber, and shall be the seconde side of the diametralle nomber: The other nomber whiche is the greater, shall alwaies be an odde nomber: and shall bee the diameter of that nōber whiche you desire. For example marke wel these formes that doe folowe.

If three bee propounded as the one side of a diametralle nomber: And you would knowe, what maie bee the other side: and what is the diametralle nomber: And thirdly, what is the diameter to that nomber: Doe, as I saied before: multiply. 3. by it self, and it will make 9. whiche is a square nomber, and an odde nomber: and therfore hath no iuste halfe. But the nighest nōmbers to the halfe, are. 4. and. 5.

Therfore I saie, that. 4. whiche is the lesser of thē twoo, is the seconde side of the diametralle nomber: and 5. beyng the greater of them, is the diameter it self.

Scholar. Now is it light inough to perceiue that the diametralle nomber is. 12: seeyng. 3. multiplied by