Hi I am still learning but something weird happened. In a new Workspace Do-it myVar := LargeInteger new Print-it myVar <error in printString: try 'Inspect it' to debug> When I inspect it I get SubclassResponsibility: LargeInteger had the subclass responsibility to implement #printOn:base: When I browse LargeInteger, then at Integer level I get a message ânewâ as follows: new self == Integer ifTrue: [ ^ self error: 'Integer is an abstract class. Make a concrete subclass.']. ^ super new I looked for new higher up in the hierarchy(super), but could not see it. Maybe I am a bit dumb still with looking up. I tried on SmallInteger a new, but got back Error: SmallIntegers can only be created by performing arithmetic. I then checked and noticed that SmallInteger actually have new and basicNew implemented (override) So the error I got on smallinteger was from the override LargeInteger has no override, but has a âsilent" error This seems a bit weird to me Just so you know I also tried Do-it myVar := LargeInteger new: 10000 Print-it myVar class. -> LargeInteger Dot-it myVar := myVar + 1 The last statement hangs the image! (Tried 3 times) Comment: 1. I am surprised that Do-it did not give me an error on the new: (there is a message is the hierarchy of new:neg and maybe the neg is optional?) 2. The new: seemed to have created 10000 LargeIntegers 3. I tried the new: also with just 5, and same result, image hang. (I thought 10,000 was maybe a very large loop for the + 1..) Did I damage something in the image maybe? I started this one just yesterday to look at MOOC week1. I do not need LargeIntegers for now but ⦠This is Pharo 6.0 64 Bit on Mac OSX Sierra 10.12.5 (iMac 27, 2.9GHz Intel Core i5, 16GB RAM) Regards Koos Brandt 0824542028