Inevitably at some time during your visit to Cambodia you’ll need to speak to a Khmer, which may involve discussing some product or service. Usually they will write down the price or show you on a calculator. This won't always be possible, however, so a few numbers are good to know:

1 moi, 2 bpee, 3 bai, 4 bpooun, 5 bprahm, 6 bprahm-moi, 7 bprahm-bpee, 8 bprahm-bai etc, 10 dop, 20 mpay, 100 roi, 1000 powan