8/4/2/1=1
8/4/2+1=2
8-4-2+1=3
8/4+2/1=4
8-4/2-1=5
8-4/2/1=6
8-4+2+1=7
(8-4)×2×1=8
8+4/2-1=9
8+4/2/1=10