Combination lock how many possible combinations?

6^4 =1296.

1111
1112
...
1116
1121
...
6666

May I suggest this as a time/cost effective alternative?

http://www.amazon.com/Lookatool-Res...d=1435358034&sr=1-1&keywords=combination+lock

 

It's counting up in base 6. In short, when a wheel or whatever goes from 6 to 1 (rollover), increment the next higher wheel by 1 (carry out to the next higher digit). Apply the same rule to every wheel, so when the 2nd wheel goes from 6 to 1, increment the 3rd wheel by 1.

If you want to give him a daily task, have him cycle through 36 trials each day. So the two lowest wheels would go through 36 trials, and the 3rd wheel would increment by 2. If the combination is random, there's a 50% chance of hitting it after 18 days. After 36 days, every combination will have been tried.

From my own experience as a kid, if he gets through every combination without it opening, then there was some sloppiness in setting the trial or in testing to see if it will open. Mine was 4 wheels with 10 numbers per wheel, so it took a lot longer to go through them all. After getting halfway through the second full cycle I gave up and filed it open. Not usable, but at that point I didn't care.

 

I agree with this. 6^4 or 1296.

 

+1296/10 = 129.6 -- therefore, it will take between 1 and 130 days to accomplish the given task.

What a fabulous waste of time!

Code:

Sub listofnumbers()

Dim a As Integer
Dim b As Integer
Dim c As Integer
Dim d As Integer
Dim x As String

    For a = 1 To 6
        For b = 1 To 6
            For c = 1 To 6
                For d = 1 To 6
  
                    x = Str(a & b & c & d)
                    ActiveCell.Value = x
                    ActiveCell.Offset(1, 0).Select
  
                Next d
            Next c
        Next b
    Next a

End Sub

 

It'll be much faster if you attach the lock to something solid (with a piece of string, or something), so that he can keep his hands wrapped around it, move the dials with his thumbs, and pull, instead of moving the dials, changing his hands so the can pull in opposite directions with his hands, then changing his hands again, moving the discs...

If you want to teach your kid something useful, get him and Arduino starter kit and have him program simple programs.

 

If he can not get it open, he might try using a stethoscope while turning the dials, listening for a distinct different sound, writing down that number, precede to the next number.