算術運算子

1. 假設 a=15 b=10

   pyuser@deyu ~/zzz$ python
   Python 3.12.9 (main, Aug 14 2025, 00:00:00) [GCC 14.2.1 20250110 (Red Hat 14.2.1-7)] on linux
   Type "help", "copyright", "credits" or "license" for more information.
   >>> a=15
   >>> b=10
   >>> a+b
   25
   >>> a-b
   5
   >>> a*b
   150
   >>> a/b
   1.5
   >>> a%b
   5
   >>> a**5      ## a的5次方
   759375
   >>> a//b      ## 除法只留整數 
   1
   >>> 32.8/9
   3.644444444444444
   >>> 32//9
   3
   >>> -32//9    ## 結果是負的時，取地板值， -3.64... ==> -4
   -4
   >>> -32.8//9
   -4.0
   >>> quit()
   

2. 算術運算子優先序

   1. **
   2. * / % //
   3. + -