Math symbols on GRE POWERPREP software

[Jupiter6]

Homework Statement

So far, I've encountered two symbols on the GRE practice tests which are unknown to me.

The first is a number in a square, like a telephone key

The second is a number with upside-down "L's" next to it

What do these mean?

 

[SammyS]

Can you scan them?

 

[Jupiter6]

Here's the boxes problem. I have no idea what this means.

 

[gneill]

The box is defining a function on its contents. It's equivalent to a function f,

f(x) = 3, if x is an odd integer; f(x) = 6, if x is an even integer.

So f(x) can take on the values 3 or 6 depending upon whether x is an odd or even integer.

 

[Jupiter6]

Oh, I see, It's an f(x) --->f(r) and f(s) substitution thing. Jeez, I've never seen functions expressed that way before.