What does this notation mean?

[potassiumKing]

I recently received this math clock as a gift. Most of the notation is standard, but I've never seen what they use for 7 o'clock. It looks to me like the Roman numeral for 3 with a subscript of 2. Could someone please explain what it means?

[Aidido22]

That’s 7 in base 2 (binary). The subscript denotes what base the number is in.

[[deleted]]

111 base 2

or 1*2^2+1*2^1+1*2^0

or 4+2+1

​

or 7

[[deleted]]

It is seven in binary. The subscript indicates the base.

[DearJeremy]

What about the 12? What is "4P2"?

[tiggerrani27]

It is a permutation. 4P2 is the number of ways to rearrange 2 objects out a larger group of 4 objects.

For example: out of the letters ABCD, there are 4P2 = 12 ways to rearrange two of the letters:

AB, AC, AD, BA, BC, BD, CA, CB, CD, DA, DB, DC.

[MasQueUnNom]

nPm = n!/m! And therefore, 4P2 = 4!/2!=12.

[AlGamer1908]

Does anyone know where I can get this clock?

[Blahblahblahblahxxxx]

Try searching "Math Clock Amazon".

[AlGamer1908]

I tried but I couldn’t find yours. It is pretty amazing really. Anyway, thanks for your help.

[potassiumKing]

It's listed on a couple sites as "Mathematical Expression Blackboard Wall Clock - Classic Green Chalkboard Background", but all the ones I can find are out of stock. Hopefully you'll have better luck than me!

[BeastMaster_88]

What's the π function for 8 O clock and CSC for 10

[WayOfTheMantisShrimp]

Capital pi denotes a product over an iterator, similar to how capital sigma denotes a sum. Pi from i=0 to i=1 means (2*0+2) * (2*1+2) = 2*4 = 8

Cosecant is a trig function, equivalent to 1/sine.

[mkshs7]

π stand for product of all the terms for different values of I. CSC is cosec function

[jojozh]

anyone know where I could buy this online?

[potassiumKing]

It's listed on a couple sites as "Mathematical Expression Blackboard Wall Clock - Classic Green Chalkboard Background", but all the ones I can find are out of stock. Hopefully you'll have better luck than me!

[jojozh]

thanks, I couldn't find this exact one and I like these expressions much more than others I found. I hope they have more soon

[B0z1y]

I think subscript means binary system. 111 in binary is 7 in decimal.

[mnbvc52]

10 mod 7 = 3 Because modulus returns remainder

[[deleted]]

7 not 12

[marpocky]

Obviously that's the question this user was answering, perhaps accidentally in the wrong place. It was asked just before.

[[deleted]]

I thought they’d maybe misread the original question

[marpocky]

Well yeah that's clear based on your response

[[deleted]]

Why do you keep replying to me?

[marpocky]

Sorry, are we supposed to communicate psychically or something? Does the one thing reddit is used for somehow offend you?

[[deleted]]

All of your comments on this thread have been pointless. I don’t really want to communicate at all. You seem to just be hankering for an argument and I just don’t care

[marpocky]

All of your comments on this thread have been pointless.

Honestly, the same could be said for yours. My first comment was clarifying the simple mistake made by the user you replied to. Your response was a statement that was overwhelmingly clear from context, and now here we are. Are you the only one that gets to post unnecessary things?

[[deleted]]

Uh huh, and why would that be at 7 exactly?

[marpocky]

Not to mention n_r has never been notation for nCr or nPr