口诀: 1 2 4 8 16 32 64 128 256 512 1024 2048 4096 8192 16384 32768 65536 131072 262144 524288 ……..
11111111 (2) 从右往左数平方 0开始
=1×20+1×21+1×22+1×23+1×24+1×25+1×26+1×27
=1+2+4+8+16+32+64+128
=255 (10)
11111111=1×20+1×21+1×22+1×23+1×24+1×25+1×26+1×27=255
1111111 =127
111111 =63
11111 =31
1111 =15
111 =7
11 =3
1 =1
10000000 = 0x20+0x21+0x22+0x23+0x24+0x25+0x26+1×27=128
1000000=0x20+0x21+0x22+0x23+0x24+0x25+1×26=64
100000=0x20+0x21+0x22+0x23+0x24+1×25=32
10000=0x20+0x21+0x22+0x23+1×24 =16
1000=0x20+0x21+0x22+1×23=8
100=0x20+0x21+1×22=4
10=0x20+1×21=2
1=1×20=1
1101.01 (2)遇小数点从左往右数平方 1开始
=1×20+0x21+1×22+1×23+0x2-1+1×2-2
=1+0+4+8+0+0.25
=13.25