Hi I'm writing a simple converter between Celcius and Farhenheit as an example to start programming. Converter >> convertFarhenheit: anInteger ^ ((anInteger - 32) / 1.8) ConverterTest >> testFToC | converter | converter := TemperatureConverter new. self assert: ((converter convertFarhenheit: 86) = 30.0). self assert: ((converter convertFarhenheit: 50) = 10). self assert: ((converter convertFarhenheit: 52) = 11.11111111111111) My problem is with ((converter convertFarhenheit: 52) = 11.11111111111111) I do not want to have such ugly test. I tried either to control the output Converter >> convertFarhenheit: anInteger ^ ((anInteger - 32) / 1.8) roundDownTo: 0.1 Not a good idea Or to compare with closeTo: self assert: ((converter convertFarhenheit: 52) closeTo: 11.11) does not work because we cannot set the precision. So at ESUG I briefly discuss that with Nicolas Cellier and I need help. Should I introduce in pharo closeTo:interval: Any suggestions that a newby can understand is welcome. Stef