00:00 A small price calculation
00:29 Start with the entry method
00:56 Const names a fixed binding
01:24 Var allows a later assignment
01:51 Multiply named values
02:18 A comparison produces a Boolean
02:45 Check the actual output
03:17 Text is not an integer
03:47 Const also catches unintended changes
04:17 Read expressions from their purpose
04:48 Be precise about what is immutable
05:17 Exercise: change the outcome
