Are numbers real?
As planners we use numbers every day of the week but how real are they?
In the western world, numbers in the form we know and use today appeared in the 13th century when Leonardo Pisano Bigollo (c. 1170 – c. 1250), known as Fibonacci an Italian mathematician, published the Liber Abaci (1202). In the book, Fibonacci advocated numeration with the digits 0–9 and place value, and showed the practical importance of the new numeral system by applying it to commercial bookkeeping, and other applications.