Belief it or not, a whole range of symbols is used as a decimal marker and thousands separator. The dot under (.) and the comma (,) are probably the most widely known, but also the dot middle (∙), dot above (˙) or comma above (') are used in various countries.
The International Bureau of Weight & Measures, has noted that only the dot or comma should be used as a decimal separator (Bureau International des Poids et Mesures, 2003, p. 169). To separate thousands only a space should be used and not a dot or comma (Bureau International des Poids et Mesures, 1948, p. 70, 2003, p. 169).
So the only two ways to write down seven million and a half are 7 000 000,5 or 7 000 000.5 (or without the spaces).
Rounding
The rounding used here is the ‘round half away from zero’. If we want to round to two decimals, this method means we look at the third decimal. If the third decimal is 5 or higher (i.e. 5, 6, 7, 8 or 9) the second decimal gets increased by one. If the third decimal is lower than 5 (i.e. 0, 1, 2, 3, or 4) the second decimal remains unchanged.
1.375999 ≈ 1.38
1.374999 ≈ 1.37
-1.375999 ≈ -1.38
-1.374999 ≈ -1.37
This is the method also described by the National Center for Education Statistics (NCES, 2012).
>>Next section: Cases, questions, variables and values
References
Bureau International des Poids et Mesures. (1948). Résolution 7 (pp. 70–71). Presented at the 9e Conférence Générale des Poids et Mesures, Paris: BIPM.
Bureau International des Poids et Mesures. (2003). Résolution 10. Presented at the 22e Conférence Générale des Poids et Mesures, Paris: BIPM. Retrieved from http://www.bipm.org/fr/convention/cgpm/comptes_rendus.html
NCES. (2012). Analysis of Data / Production of Estimates or Projections. In 2012 NCES Statistical Standards. Retrieved from http://nces.ed.gov/statprog/2012/pdf/Chapter5.pdf
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