Thanks for your very detailed reply, this has inspired me to learn more about basic maths and indeed Excel. This is the first time I have fallen foul of the floating point anomaly and it's certainly given me much to think about when interpreting displayed results. Maybe I should have changed the spreadsheet's setting to 'set precision as displayed'. Out of curiosity, when calculating your example:
0.24 0.239999999999999,9911182158029987476766109466552734375
1.24 1.23999999999999,99911182158029987476766109466552734375
3.24 3.24000000000000,02131628207280300557613372802734375
32.24 32.2400000000000,0198951966012828052043914794921875
how did you manage to calculate such a long string of numbers after the decimal point? I'm assuming Excel won't do this.