Binary Fingers!

Forget about counting to 10 on your fingers ... you can count past 1,000 if you want!

Right Hand

With just your right hand you can count to 31:

hand 0
No fingers up is 0
hand 1
Thumb is 1
hand 2
Index finger is 2
hand 3
2 and 1
makes 3
hand 4
Middle finger is 4
hand 5
Add your thumb
for 5
hand 6
4 and
2 makes 6
hand 7
4 and 2 and 1
makes 7
hand 8
Fourth finger is 8

... and continue the pattern:

  • add your thumb (+1) to make 9,
  • or add your index finger (+2) to make 10
  • or add thumb (+1) and index finger (+2) to make 11
  • etc.

In fact you are counting in Binary:

Number Made by hand right: 16,8,4,2,1
1 1         up
2 2       up  
3 2+1       up up
4 4     up    
5 4+1     up   up
6 4+2     up up  
7 4+2+1     up up up
8 8   up      
9 8+1   up     up
10 8+2   up   up  
11 8+2+1   up   up up
12 8+4   up up    
13 8+4+1   up up   up
14 8+4+2   up up up  
15 8+4+2+1   up up up up
16 16 up        
17 16+1 up       up
  etc....          

Here are some more examples:

hand 26
16+8+2
makes 26
hand 30
16+8+4+2
makes 30

 

 

 

 

Why?

So you can count to bigger numbers when you don't have a pencil or paper.

You can also "remember" numbers by holding your fingers in the right way.

Or you can show someone a secret number using just your hand (or hands, see later).

Your Turn

Practice counting from 0 to 31 on your fingers, just like above.

Do it many times until it becomes easy.

When you can do it well, demonstrate it to your friends!

Left Hand

Want bigger numbers? Your left hand can help:

hand both: 512,256,128,64,32,16,8,4,2,1

Now we can use all 10 fingers to make numbers like these:

hand 34
32+2
makes 34
hand 60
32+16+8+4
makes 60
hand 803
512+256+32+2+1
makes 803

And lastly, what happens when all fingers are up?

hand 1023
512+256+128+64+32+16+8+4+2+1
makes 1,023

So now you can count just past 1,000 using only 10 fingers. Wow.

Practice this over the next few days ... you will gain a new skill and also find binary much easier to understand.