The math problem of the second grade in Yancheng, Jiangsu Province from 2007 to 2009 shows the change of the number of red-crowned cranes: 654 in 2007 and 60 1 in 2008.
The answer is 0, according to the increasing and decreasing speed of (654-601= 53,601-502 = 99) 53,99, that is to say, the quantity in each year will decrease more than that in the previous year, that is, 100 is at least less than that in 2009/kloc-. Compared with 1 10,1has at least 10 1 3 and at least 102. Therefore, 502-100-10/-102-103-104 =-10, so10.