Now an arithmetic exercise from an Arabic book dated Baghdad, 1321

For me, it is a mystery the exclusion of Arabic Mathematics in daily science.

In Venezuela, was popular when I study in High School a book about Arabic Arithmetic: "El Hombre que Calculaba", "The man capable to make mental Calculus".

The problem I am offering today, is "The Four Fours".

According to this Math, it is possible to represent any natural number using four fours.

So, we have, for the first 10 numbers,

• 44-44 = 0.
• 44/44 = 1,
• 4/4+4/4 = 2,
• 4+4+4/4= 3,
• 4 + (4-4)/4 = 4,
• (4 x 4 + 4)/4 = 5,
• (4+4)/4 + 4 = 6,
• 44/4 - 4 = 7,
• 4 + 4 + 4 - 4 = 8
• 4+4+4+4/4 = 9,
• 44 - 4/4 =10

What about the others? 11,12,...

I found on the Web a problem similar, logically with the same root uncommented.

Friends, You can also read the book from Divulgative Mathematics Subject. Spanish in requeried.