Question 38
A digit is a “godchild” of a natural number if it is the units digit of one of that number's divisors. For example, the divisors of $56$ are $1,2,4,7,8,14,28,56$, so its godchildren are $1,2,4,6,7,8$.
a) What are the godchildren of $57$?
b) Find a number having $7,9$ as godchildren but not $3$. What are all its godchildren?
c) Explain why $2,5$ are godchildren of any number having $0$ as a godchild.
d) Explain why $8$ is a godchild of any number having both $0,9$ as godchildren.
a) What are the godchildren of $57$?
b) Find a number having $7,9$ as godchildren but not $3$. What are all its godchildren?
c) Explain why $2,5$ are godchildren of any number having $0$ as a godchild.
d) Explain why $8$ is a godchild of any number having both $0,9$ as godchildren.