Huh? Do comic book characters face the other way up there, or something?
Yay---Moonie's come to play! or growl, or summat!
Seeing as how 'cut' was not defined as cutting through one thickness, the plank can be cut into ten equal lengths with four cuts.
The first cut cuts the plank into two equal halves. These are stacked one on top of the other so that the second cut can be through both
The second cut cuts one fifth off the length giving two 'finished' pieces.
The third cut cuts the remainder at the center and these are stacked one on top of the other
This pile is cut through the center and that gives the required eight pieces to make up the ten.
And for those that were concerned about the measuring; this requires less measuring too.
Of course you could then say that a double cut would take longer than a single cut. This is true - though it was not included in the question - but my way I still cut through the same total thickness of wood and with less measuring and considerably less lifting the wood into position, so I will still be on my second beer by the time you get to the bar!!!
@markr,
Assuming that it takes him a minute to cut through it because of it's thickness, stacking them wouldn't get it done any quicker, but it would cut down on measuring time.