What is both numbers can go into 45 and 63?

The numbers that can go into both 45 and 63 are their common divisors. The greatest common divisor (GCD) of 45 and 63 is 9, which means 9 is the largest number that divides both. Other common divisors include 1 and 3. Therefore, the common divisors of 45 and 63 are 1, 3, and 9.