Question 5
A student had to multiply a 3-digit number by a 4-digit number (the numbers do not start with 0). Instead of doing so, he simply wrote the 4-digit number to the right of the 3-digit number, obtaining as a result a 7-digit number which is $N$ times ($N \in \mathbb{N}$) larger than the correct result.
a) Can $N$ be equal to 2 or 10?
b) Find the largest possible value of $N$.
a) Can $N$ be equal to 2 or 10?
b) Find the largest possible value of $N$.