I need someone to measure a mattress for me, but he says he can't because he has nothing to measure it with. I'm currently about 800 miles away from him, so I can't just take the bull by the horns and drive over there to help.
Is there a trick I can suggest him to use, which does not involve any measuring tools? All I need to know is whether it's roughly 140, 160 or 180 cm wide. I don't need the measurement to be very precise.