A Cantor expansion is a sum of the form $$a_n n! + a_{n-1} (n-1)! + \dots a_2 2! + a_1 1!$$ where $0 \leq a_i \leq i$ are integers for $i = 1,2,\dots n$.
For example, the Cantor expansion of 17 is $17 = 2(3!) + 2(2!) + 1(1!).$ Note that $17 = 1(3!) + 5(2!) + 1(1!)$ is correct but is not a valid Cantor expansion of 17 since we insist the coefficient of n! is no more than n. Thus the coefficient of 2! should be a 0,1 or 2 for example.
Complete the following Cantor expansions of:
(a) $4$ = $(3!)$ + $(2!)$ + $(1!)$

(b) $545$ = $(5!)$ + $(4!)$ + $(3!)$ + $(2!)$ + $(1!)$

(c) $56$ = $(4!)$ + $(3!)$ + $(2!)$ + $(1!)$