Post #4114491
2026-07-13 03:33 UTC
6/7
Where we can clearly see Cajori using a:(bc) and a:bc as equivalent expressions, which is precisely because bc=(b X c) BY DEFINITION, as already discussed at https://dotnet.social/@SmartmanApps/110846452267056791. This was what Lennes failed to understand - he kept calling Products "Multiplication", even though it's IN BRACKETS, and thus done in the BRACKETS step, as he observed every textbook doing. He said it was an "exception to the rule", whereas in fact it's the ACTUAL rule, ab=(a X b), as per Cajori page 272...
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@SmartmanApps@dotnet.social 2026-07-13 03:34
7/7 So when people say "Cajori said there was no agreement about whether to do 2(4) first or not"... 1. No, he didn't. He was talking about literal multiplication, with a multiply sign 2. he uses a/bc and a/(bc) as equivalent expressions on page 272, as every textbook (then and now) does (except for those using Lennes' made up wrong rule), because that's ALWAYS been the rule, ab=(a X b), as, even before Brackets started being used in Maths, aa was already the notation for a Product