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Radmila Gavrilov

rank
177
points
19
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short ranking list
175. Nenad Golubovic 19
176. Digvijay Singh 19
177. Radmila Gavrilov 19
178. Gemini Tay 19
179. Daniela Jakubovski 19
last 3 solved tasks
Look at the series (1, 5, 15, 30, 150, 450, 900, 4500, ?), determine the pattern, and find the value of the next number!
What number should fill in the blank? (8, 43, 11, 41, ?, 39, 17)
What will be the missing number? (9, 19, 40, ?, 170)

First dated printed arithmetic book

In 1478, the anonymous Arte dell'Abbaco(“The Art of the Abacus”), printed in Treviso, Italy had this publication date. It is the first dated printed book on arithmetic. The unknown author was likely a priest, and it was dedicated to some of his young friends who kept asking for it. The printer was probably Geradus de Lisa, dé Flandria. The 124-page text dealt with commercial applications of arithmetic, so the language was the local vernacular Venetian dialect, not the scholarly Latin used for the abstract studies of universities. The book teaches the four main operations, with numerous examples, and the concept of fractions (but not the as yet unknown decimals). He shows how to calculate the date of the new Moon. Although some pamphlets on Algorithmus are possibly older than this book, they are undated.«[Image: detail of a calculation shown in the book.]

Charlie Viracola: Believed in Santa

Christmas always sucked when I was a kid because I believed in Santa Claus, and unfortunately, so did my parents.
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