There’s a joke - something about Xmas and Halloween, I can’t remember the whole joke - with the punchline “because Dec 25 = Oct 31!”

I’ve never been able to figure this one out. I don’t know octal, but I know decimal and binary, and I assume that octal would just be base 8, is that correct?

Wouldn’t that make Oct 31 = Dec 32 instead of Dec 25?

The only way the joke makes sense is if the first place holder is itself and the second is x8 (3*8 + 1 = 25), which would seem to make for an inconsistent number system.

How are you figuring Oct31 = Dec32? I’d be interested to see how you got that answer. Going to a larger base the number can’t get larger.

Just as the columns in decimal go … 10[sup]3[/sup], 10[sup]2[/sup], 10[sup]1[/sup], 10[sup]0[/sup], i.e. … 1000s, 100s, 10s, 1s , and those in binary go with powers of 2 (… 64s, 32s, 16s, 8s, 4s, 2s, 1s), so octal goes …512s, 64s, 8s, 1s.

So 25 in Decimal would equate to 3 lots of 8 plus 1 lot of 1 = 31 in octal. Similarly 100 in Decimal would be 1x64 + 4x8 + 4x1, or 144 in octal.

Because, sometimes, mathematic notation doesn’t work for those of us who don’t use it on a regular basis.

Another way is to pull up the calculator on your computer, type in 31, then change it to octal to see the value. There’s probably an oct button on there somewhere.

Bingo. IIRC the title is “The Family Man” and involves an IRS agent tracking down a computer crook.

The connection is deeper than just base 10 and base 8, because the root words of December and October mean “10” and “8” respectively, and at one point those were the 10th and 8th months of the calendar.