Four things must be known in Duplation. ¶ This is the Chapture of [duplacioɳ], in þe quych craft þou most haue & know 4 thinges. ¶ Þe first þat þou most know is what is duplacioɳ. þe secunde is how mony rewes of figures þou most haue to þis craft. ¶ þe thryde is how many cases may[6] happe in þis craft. ¶ þe fourte is what is þe profet of þe craft. Here they are. ¶ As for þe first. duplacioɳ is a doublynge of a nombre. ¶ As for þe secunde þou most leaf 146 b. *haue on nombre or on rewe of figures, the quych called numerus duplandus. As for þe thrid þou most know þat 3 diuerse cases may hap in þis craft. As for þe fourte. qwat is þe profet of þis craft, & þat is to know what [a-risyȝt] of a nombre I-doublyde. Mind where you begin. ¶ fforþer-more, þou most know & take gode hede in quych side þou schalle be-gyn in þis craft, or ellis þou mayst [spyl] alle þi laber þere aboute. certeyn þou schalt begyɳ in the lyft side in þis Craft. thenke wel ouer þis verse. ¶ [7]A leua dupla, diuide, multiplica.[7]
The [sentens] of þes verses afore, as þou may see if þou take hede. Remember your rules. As þe text of þis verse, þat is to say, ¶ Si vis duplare. þis is þe sentence. ¶ If þou [wel] double a nombre þus þou most be-gynɳ. Write a rewe of figures of what nombre þou welt. versus.
Postea procedas primam duplando figuram
Inde quod excrescit scribas vbi iusserit ordo
Iuxta precepta tibi que dantur in addicione.
How to work a sum. ¶ Here he telles how þou schalt worch in þis Craft. he says, fyrst, whan þou hast writen þe nombre þou schalt be-gyn at þe first figure in the lyft side, & doubulle þat figure, & þe nombre þat comes þere-of þou schalt write as þou diddyst in addicioɳ, as ¶ I schal telle þe in þe case. versus.
The Cases of the Craft of Duplation.
* ¶ Nam si sit digitus in primo limite scribas.
If the answer is a digit, ¶ Here is þe first case of þis craft, þe quych is þis. yf of duplacioɳ of a figure arise a digit. what schal þou do. þus þou schal do. write it in the place of the top figure. do away þe figure þat was doublede, & sett þere þe diget þat comes of þe duplacioɳ, as þus. 23. double 2, & þat wel be 4. do away þe figure of 2 & sett þere a figure of 4, & so [worch] forth tille þou come to þe ende. versus.
¶ Articulus si sit, in primo limite cifram,