The Message Way of Life

Exercise 2.1

'Hello' 
   at: 1 put: $B;
   at: 2 put: $e;
   at: 3 put: $l;
   at: 4 put: $l;
   at: 5 put: $e;
   yourself

Exercise 2.2

1 + (1/2) squared + (1/3) squared + (1/4) squared
⇒  205 / 144

Exercise 2.3

From a System Browser, do from the left panel to the right ...Kernel-Text → CharacterSequence → arithmetic... the count of methods in the last right panel is 6: *, +, -, /, // and \\.

An alternative is to search for a class with a keyboard shortcut: Ctrl-Space from the Cuis-Smalltalk environment or Ctrl-f from the class category of the Browser.