1 )

0101 = 5

11000 = 24

010101 = 21

11101101 = 237

2)

1 = 01

3 = 11

3)

7 = 111

9= 1001

4)

0 = 00000000

100 = 01100100

25 =00011001

258 = impossible ( 128+64+32+16+8+4+2+1 = 255 : 11111111)

5)

000010110100 (si on suis le sens de lecture)

001011010000(si on suis la flèche du temps)