Extend cord on Numeric Keyboard
I've just bought a new iMac and chose to get the numeric keyboard over the wireless one because I didn't want to bother with batteries and I felt the extra usb ports would be handy for general jobs. However, I have a 3 level desk and while the keyboard does manage to reach a usb port behind the computer, I can't pull out my designated keyboard shelf in order to use it more ergonomically. I've heard there's meant to be an extension cord included but I may have missed out as I got mine with a computer? Is there any way around this, I'm not sure I can use it very well if the keys aren't even virtually visible to me.
iMac, OS X Yosemite (10.10.2)