Write a C program for decimal to factorial number system conversion and vice versa?

Question

Decimal to Factorial
23(D) = 3210(F)

23 / 3! = 3 (5)
5 / 2! = 2 (1)
1 / 1! = 1 (0)
0 / 0! = 0 (0)

Factorial to Decimal
3210(F)=23(D),
3*3!+2*2!+1*1!+0*0! = 23(D)

Comments

what is the range of input?