Until recently, Taiwan elementary mathematics curriculum has been changing for several times. The aim of this study is to refer to various curriculum reforms, and focus on the way ¡§Number and Calculation Standards¡¨ changed in the history of reforms. The specific objectives of this study: to refer to one curriculum standards and its subsequent standards and do pair wise comparison. To achieve the above objectives, the investigator referred to 7 target versions of mathematics curriculum standards: 41, 51, 57, 64, 82, 89, 92 (R.O.C year). The comparison was done qualitatively, using historical research methodology. The main research findings are the differences in the above 6 pair wise comparisons. 1. The change from Year 41 to Year 51: In the Year 51, the part on Writing numbers in Chinese characters was de-emphasized. Emphasis was on Ordinal numbers, division thinking, mental arithmetic and written algorithm. The size of numbers reduced to 4-digits (due to a change in currency, 4 dollars to 1 New Taiwan dollar). 2. The change from Year 51 to 57: more focus on symbols, did not require the revision on what was learned in previous year. 3. The change from Year 57 to 64: de-emphasized on mental arithmetic and written calculation; emphasized on Inverses, multiplication/division on ¡§0¡¦ and ¡§1¡¨, ratio, approximation, negative numbers and use of electronic calculators. 4. The change from Year 64 to 82: no need to include negative numbers and abacus. Emphasized on two-step problems, number line, and reading multiplication tables. 5. The change from Year 82 to 89: de-emphasis on odd and even numbers; emphasis on realistic contexts, understanding vertical algorithm. 6. The change from Year 89 to 91: no need to use calculators to check working; emphasis on vertical algorithm, whole number calculations, and the connections of multiples/factors, rate/speed, and, fractions/decimals.