(1)108.1944
解:2x3=6,3x6=18,6x18=108,6x108=1944
(2)22.29.37.46
解:1+1=2,2+2=4,4+3=7,7+4=11,11+5=16,16+6=22,22+7=29,29+8=37,37+9=46
(3)1890.20790
解:2x3=6,6x5=30,30x7=210,210x9=1890,1890x11=20790
(4)714.7134
解:15x2+6=36,36x10-6=354,354x2+6=714,714x10-6=7134
(5)239.2389
解:13x1+10=23,23x10-1=229,229x1+10=239,239x10-1=2389