I ordered a concrete truck today to fill the floors on my house. The area that was being filled in is 46 square meters (100mm depth). The concrete man claims that he has put in 7 cubic meters of concrete which makes no sense - the area is not big enough. To confound it further, he had a counter at the back of his truck which counted up to 4900 or so - he is saying that this doesn't measure cubic meters but he has to translate it on some table he's got. Whats going on here and how can I prove one way or another how much concrete I had?