Permutation Expressions: Understanding and Computing

[kathrynag]

Homework Statement

Compute the expression shown for the permutations
1.$$\left|<\phi>\right|$$
2..$$\left|<\tau^2>\right|$$
3.$$\phi^{100}$$
where:
$$\phi$$= top row:1, 2 , 3 ,4 , 5 ,6
bottom row: 3,1, 4,5,6,2

$$\tau$$ = top row: 1,2,3,4,5,6
bottom row: 2,4,1,3,6,5

Homework Equations

The Attempt at a Solution

Ok, my main problem is that I don't even know what they're asking. I understand how to do permutation multiplication and composition, but not this.
I do know from the back of the book that #2 is 2, but I want to know why this is true.

 

[kathrynag]

Does it just mean finding the identity?