分數：fractions

　　分子：numerator

　　分母：denominator

　　分數的加減乘除：addition，subtraction，multiplication and division of fractions

　　繁分數和假分數：mixed number and improper fraction

　　繁分數是指一個數由一個整數和一個分數構成。

　　假分數是指分子大于分母的分數。例如：7/3

　　小數：decimals

　　科學計數法：scientific notation

　　Sometimes decimals are expressed as the product of a number with only one digit to the left of the decimal point and a power of 10. This is called scientific notation. For example, 231 can be written as 2.31102 and 0.0231 can be written as 2.3110-2. When a number is expressed in scientific notation, the exponent of the 10 indicates the number of places that the decimal point is to be moved in the number that is to be multiplied by a power of 10 in order to obtain the product. The decimal point is moved to the right if the exponent is positive and to the left if the exponent is negative. For example, 20.13103 is equal to 20,130 and 1.9110-4 is equal to 0.000191.