You can count to 1023 with both hands. Let's try! I'm always frustrated by about 200 to 300. ;D
The number counted to by a single hand is ordinarily 5 or 10.
31 is countable by a single hand with the binary system. If both hands are used, counting to 1023 is possible.
left hand 
right hand
Rule 1 (Decadal system)
the thumb=[ 1 ], the index finger=[ 2 ], the middle finger=[ 4 ], the ring finger=[ 8 ], the little finger=[ 16 ]
If both hands are used, another hand is fingers are assigned [32], [64], [128], [256], [512].
A number is read by combining the finger standing and the finger folded.
Rule 2 (Binary system)
The standing fingers=[ 1 ] , The folded fingers=[ 0 ]
The finger expresses,It turns out that decadal system and binary system correspond.
samples
| decadal | 1 | 8+2= 10 | 16+4= 20 | 16+8+4+1= 29 |
|---|---|---|---|---|
 |  |  |  | |
| binary | 1 | 1010 | 10100 | 11101 |
*** It's interesting in arithmetic. ***
It will shift to the left if it doubles.
| decadal | 10 | 20 | 40 | 80 |
|---|---|---|---|---|
| binary | 1010 | 10100 | 101000 | 1010000 |