Hi!

Finally decided to seek for online help after repeatedly banging my head to the wall with an annoying problem. It's a fault in my thinking but I just can't seem to be able to shake it off.

So, I know what decimals and sig figs are and I'm very familiar with the general rounding rules of +/-/*/: -calculations with measured values. It goes brilliantly as long as I don't think about it. But sometime ago I stopped to think about the difference of accuracy and precision andthereI got lost. See, in my native language those two are rarely separated when it comes to the rounding rules. The same word is basically used for both although they are very different concepts. Anyhow, I'm fine withprecision- no problem there. But does anyone have a magic trick to make my brain understand accuracy? I'll elaborate:

1) A = 12,5 cm * 0,7 cm = 8,75 cm^{2}9 cm^{2}, because 0,7 cm has less sig figs as 12,5 cm

The precision of values is the same, but why is 0,7 cm considered to bethe less accurate valueso that the sig fig rounding rule can be applied? Even my teacher friends were baffled by my problem, because they'd just accepted the rule without ever thinking.

2) A = 0,123 m * 1200 m = 147,6 m^{2}150 m^{2}, because 1200 m has less sig figs as 0,123 m

Again I fail to understand the accuracy aspect. What makes 1200 m the less accurate value? If you answer me, that it's because of the sig figs, I'll just carry on banging my head to the wall...

Cheers in advance,

F

PS: Pardon my non-fluent English.