81 De rotulis¹⁸⁰

Rotuli 37 valent libras 11; quantum

⓪ £ ℞ 11 37 ⓪ ⑦ per 11   \({12~~\phantom{1}0~~\phantom{1}7 \over 37~~12~~20}\) 5 18

¹⁸¹ valent ergo rotuli 18? Multiplica 11 per 18; erunt 198, que multiplica per 12 et per 20, hoc est per 240 ut habeamus ea¹⁸² in virgula; erunt 47520, que divide per \({\phantom{1}1~~\phantom{1}0~~\phantom{1}0 \over 37~~12~~20}\); exibunt \({12~~0~~7 \over 37~~12~~20}\) 5 pro pretio de rotulis 18

82 De eodem

Item rotuli 42 valent libras \({1 \over 5}\) \({1 \over 4}\) 13; quantum valent ergo rotuli \({1 \over 2}\) 18?

⑤ 269 £ ℞ \({1 \over 5}\) \({1 \over 4}\) 13 42 ⑨ ④ pensa per 11 37 \({6~~\phantom{1}5~~18 \over 7~~12~~20}\) 5 \({1 \over 2}\) 18

¹⁸³ Multiplica 13 per suas vir[R:63r]gulas: erunt 269, et multiplica 18 per 2 et adde 1; erunt 37, que multiplica per 269: erunt 9953, que divide per regulam de 42, scilicet per \({1~~0 \over 6~~7}\) et per 2 et per 4 et per 5 que sunt sub virgulis amborum numerorum, coaptans eos sic: quod de \({1 \over 2}\) et \({1 \over 6}\) facies \({1 \over 12}\) et de \({1 \over 4}\) et \({1 \over 5}\) facies \({1 \over 20}\), et habebis in eorum coaptatione \({1~~\phantom{1}0~~\phantom{1}0 \over 7~~12~~20}\); exibunt libre¹⁸⁴ \({6~~\phantom{1}5~~18 \over 7~~12~~20}\) 5 pro pretio illorum rotulorum \({1 \over 2}\) 18

83 Nunc satis dictum est de venditionibus cantarium¹⁸⁵ et aliorum diversorum ponderum pro libris denariorum, in quibus [V:37r] indigemus habere in virgulis¹⁸⁶ divisionum ipsorum \({\phantom{1}1~~\phantom{1}0 \over 12~~20}\) ut habeamus libras, soldos¹⁸⁷ et denarios in una multiplicatione. Nunc de eorum venditionibus factis a soldis, in quibus indigebimus¹⁸⁸ habere tantum \({1 \over 12}\) in [G:65r] capite virgularum divisionum ipsorum, ut que super 12 ex divisionibus remanserint¹⁸⁹ fiant denarii, cum ea que ex divisionibus¹⁹⁰ extra virgulam exierint sint¹⁹¹ soldi.