=IF(A1<=500,2,IF(A1<=1000,4,IF(A1<=1500,6,IF(A1<=2000,8,IF(A1<2500,"未定义",10)))))
=LOOKUP(MOD(A1,1000),{0,1,101,201,……,901},{0,290,410,456,……,770}*100+(A1>=1000)*77000)省略号处换成具体数字