Solve for the missing number in the following division problems: a) □ ÷ 9 = 111, b) □ ÷ 40 = 12, c) 350 ÷ □ = 5, d) 525 ÷ □ = 5

$$\square = 999$$

The missing number is $\boxed{999}$.

$$\square = 480$$

The missing number is $\boxed{480}$.

$$\square = 70$$

The missing number is $\boxed{70}$.

$$\square = 105$$

The missing number is $\boxed{105}$.