Subtracting a directed number by taking away ([size=100]represented [/size]by "[b][size=100][size=150]×[/size][/size][/b]") the "+1" or "−1" counters.

[u]Reference[/u][br]Kaner, P.A. (1964) 'The addition and subtraction of negative numbers', [i]The Mathematical Gazette[/i], [b]48[/b](364), 183-185. [url=https://www.jstor.org/stable/3613541]https://www.jstor.org/stable/3613541[/url]