How do you convert $\displaystyle 14in^2$ to $\displaystyle m^2$ ?
So as long as it is exact, you don't mind that it is wrong?
1 inch is approximately 2.54 cm, just as 1 meter is approximately .0254 meters. Both statements have exactly the same accuracy and, in fact, say exactly the same thing.
$\displaystyle \displaystyle 14\ \text{in}^2=(14\ \text{in}^2)\left(\frac{2.54\ \text{cm}}{1\ \text{in}} \right)^2\left(\frac{1\ \text{m}}{100\ \text{cm}} \right)^2$
I think maybe you have been misinformed.
The yard is defined in terms of the metre. (source) I learned it as the inch being defined in terms of centimetre which amounts to the same thing.
The metre is defined in terms of the speed of light traveling at a certain fraction of a second. (source)
The second is defined in terms of the radioactivity of the caesium 133 atom. (source)
By the way I wasn't contradicting Educated's post; I realise they are the same precision/accuracy. I mentioned that I like to use 1 inch = 2.54 cm as a general statement; for example, I would generally not use 1 mile $\displaystyle \approx$ 1.61 km but instead convert the long way.