2011 minus 1 / 2, then minus the remaining 1 / 3, then minus the remaining 1 / 4, and so on, until finally minus the remaining 1 / 2011, find the last remaining number

2011 minus 1 / 2, then minus the remaining 1 / 3, then minus the remaining 1 / 4, and so on, until finally minus the remaining 1 / 2011, find the last remaining number

2011*1/2*2/3*3/4*.*2010/2011=1