Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ π -¹ ² ³ °

You are not logged in.

- Topics: Active | Unanswered

**MargaritaMc****Member**- Registered: 2013-02-11
- Posts: 9

I find myself getting stuck on the NAMES 'commutative', 'distributative' and 'associative' - they are introduced in the Kindergarten level at the website...

Has anyone got a mnemonic for remembering them?

Margarita

Offline

**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,787

hi Margarita,

Haven't got a 'mnemonic' as such but this is what I do:

Commutativity:

A x B = B x A etc

At rush hour people from town A get in their cars and drive to work in town B. And people in town B get in their cars and drive to work in town A. At the end of the day, they all swap back. I believe that's why they are called **commuters**; because they swap over.

Associativity:

If you've got three numbers to multiply / add / divide etc, which ones do you** associate** together first?

A # B # C ?

Is it A # B, get the answer and then do (answer # C)

Or is it B # C, get the answer and then do (A # answer).

So it's all to do with the ones you **associate** together first.

# is an associative operation if

(A # B) # C = A # (B # C)

Distributivy:

A # (B @ C) where # and @ are different operations you can do with 2 numbers.

So A has to be **distributed** to the contents of the bracket; B gets it and C gets it:

(A # B) @ ( A # C)

You are probably learning which operations are commutative, associative and distributive over another operation.

What is correct in each case is much more important than remembering the correct word, so I shouldn't worry too much about them.

Hope that helps,

Bob

*Last edited by bob bundy (2013-02-13 00:29:09)*

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

Offline

**MargaritaMc****Member**- Registered: 2013-02-11
- Posts: 9

Thank you again, Bob. Yes, the ideas are easier than the names!

I was doing the exercises at the mathopolis link where they ask you to click on which law was in operation for a given equation. I knew what the equations were ** doing ** but I kept getting the name wrong!

Margarita

Offline