+----------------------------------+---+---+---+---+---+ | The remenaunt | 2 | 9 | 9 | 9 | 9 | +----------------------------------+---+---+---+---+---+ | Wherof me shall{e} w{i}t{h}-draw | 3 | 0 | 0 | 0 | 3 | +----------------------------------+---+---+---+---+---+ | The nombre to be w{i}t{h}-draw | | | | | 4 | +----------------------------------+---+---+---+---+---+ [Sidenote: A justification of the rule given. Why it is better to work from right to left. How to prove subtraction, and addition.] And whan me cometh{e} to the nombre wherof me intendith{e}, there remayneth{e} all{e}-wayes .10. ffor þe which{e} .10. &c. The reson why þat for eu{er}y cifre left behynde me setteth figures ther of .9. this it is:--If fro the .3. place me borowed{e} an vnyte, that vnyte by respect of the figure that he came fro rep{re}sentith an .C., In the place of that cifre [passed over] is left .9., [which is worth ninety], and yit it remayneth{e} as .10., And the same reson{e} wold{e} be yf me had{e} borowed{e} an vnyte fro the .4., .5., .6., place, or ony other so vpward{e}. This done, withdraw the second{e} of the lower ordre fro the figure above his hede of þe omyst ordre, and wirch{e} as before. And note wele that in addicion or in subtracc{i}o{u}n me may wele fro the lift side begynne and ryn to the right side, But it wol be more p{ro}fitabler to be do, as it is taught. And yf thow wilt p{ro}ve yf thow have do wele or no, The figures that thow hast withdraw, adde them ayene to the omyst figures, and they wolle accorde w{i}t{h} the first that thow haddest yf thow have labored wele; and in like wise in addicio{u}n, whan thow hast added{e} all{e} thy figures, w{i}t{h}draw them that thow first [*Fol. 50b] addest, and the same wolle reto{ur}ne. The subtraccio{u}n is none other but a p{ro}uff{e} of the addicio{u}n, and the contrarye in like wise. [Headnote: Chapter IV. Mediation.] [Sidenote: Definition of mediation. Where to begin. If the first figure is unity. What to do if it is not unity.]