How effective is this workout calorie burning wise?

i see personal trainers make heavy people do this all the time; they have them get on the ground on their stomaches, than get back up, down again, back up, over and over and over. im a teenage girl who wants to drop about ten pounds, so how effective is it on me if i do it like 100 or more times? it gets me dripping with sweat, any idea how effective it is?