The nines test or better known popularly as nines away is a method that was widely
used in the last century, being found in didactic books and multiplication tables. People
who often worked with math used this method to quickly check their calculations. The
nines test or better known popularly as nines away is a method that was widely used
in the last century, being found in didactic books and multiplication tables. People
who often worked with math used this method to quickly check their calculations. At
the end of the twentieth century with the evolution of technology and the emergence of
other methods of verication, the nines out was no longer presented in textbooks, and
thus gradually ceased to be presented in the classroom, but only as a social context. The
rst records about nines abroad were in the ninth century in Arabic arithmetic, being
traversed throughout Europe, until reaching the Brazilian textbooks. Understanding
the math that is involved in this method helps us understand why it is no longer used
in textbooks and so at school. Nines out is the rest of dividing a number by 9, being
in the range of 0, ..., 8, another way to nd nines out of a number is by adding all its
digits and dividing it by 9. This method has aws, so it is one of the reasons that is no
longer seen in textbooks and consequently in schools, being only in the social context.
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