Chapter III. Subtraction.
Definition of Subtraction. Subtraccioun is of .2. proposede nombres, the fyndyng of the excesse of the more to the lasse: Other subtraccioun is [ablacioun] of o nombre fro a-nother, that me may see a [some] left. The lasse of the more, or even of even, may be withdraw; The more fro the lesse may neuer be. How it may be done. And sothly that nombre is more that hathe more figures, So that the last be signyficatifes: And yf ther ben as many in that one as in that other, me most deme it by the last, other by the next last. What is required. More-ouer in with-drawyng .2. nombres ben necessary; A nombre to be withdraw, And a nombre that me shalle with-draw of. The nombre to be with-draw shalle be writ in the lower ordre by his differences; Write the greater number above. The nombre fro the whiche me shalle withe-draw in the omyst ordre, so that the first be vnder the first, the seconde vnder the seconde, And so of alle others. Subtract the first figure if possible. Withe-draw therfor the first of the lowere ordre fro the first of the ordre above his hede, and that wolle be [other] more or lesse, oþer egalle.
| The remanent | 20 |
| Wherof me shalle withdraw | 22 |
| The nombre to be withdraw | 2 |
| The remanent | 2 | 2 |
| Wherof me shalle with-draw | 2 | 8 |
| Þe nombre to be withdraw | 6 |
yf it be egalle or even the figure sette beside, put in his place a cifre. And yf it be more put away þerfro als many of vnitees the lower figure conteynethe, and writ the residue as thus
| *Remanens | 2 | 2 | 1 | 8 | 2 | 9 | 9 | 9 | 8 |
| A quo sit subtraccio | 8 | 7 | 2 | 4 | 3 | 0 | 0 | 0 | 4 |
| Numerus subtrahendus | 6 | 5 | [7] | [6] | . | . | . | . | 6 |
If it is not possible ‘borrow ten,’ And yf it be lesse, by-cause the more may not be with-draw ther-fro, borow an vnyte of the next figure that is worthe 10. Of that .10. and of the figure that ye wolde have with-draw fro and then subtract. be-fore to-gedre Ioynede,
| The remanent | 1 | 8 |
| Wherof me shalle with-draw | 2 | 4 |
| The nombre to be with-draw | 0 | 6 |
with-draw þe figure be-nethe, and put the residue in the place of the figure put a-side as þus:—
If the second figure is one. And yf the figure wherof me shal borow the vnyte be one, put it a-side, and write a cifre in the place þerof, lest the figures folowing faile of thaire nombre, and þan worche as it shewith in this figure here:—