Are Arabic numbers based on angles?

Answer 1

Absolutely not. so called 'Arabic' numerals are based on older Brahmi numerals, which were based on Roman Numerals for 1,2 & 3, then possibly on the Brahmi alphabet.

1, 2 & 3 were (probably) actual counting representations (I, II, III), but shown horizontally rather than vertically. The 2 & 3 probably got joined up over time as a quicker way of writing them, and as the purpose moved from a counting representation (two lines = two items) to a symbolic one (numbers as symbols rather than pictograms of what they represent).

Every so often, a powerpoint presentation turns up with some numbers drawn very weirdly (supposedly the 'ancient' form of the numbers), and angles counted arbitrarily (count only internal angles for 4 and 6, count internal AND external for 8, keep adding lines until you have enough angles for 9, and so on). It's an old fantasy that has been around for several hundreds of years, put forward by people who simply can't bear the idea that our representation of numbers came about pretty much spontaneously, and prefer to think they were somehow designed from scratch.

Hope this answers your question.