Calculate the following pairs: a) (328 ÷ 4) ÷ 2; 328 ÷ (4 ÷ 2) b) 144 ÷ (6 ÷ 3); (144 ÷ 6) ÷ 3

    $$
    328 \div 4 = 82
    $$

    $$
    82 \div 2 = 41
    $$
    The first expression equals $\boxed{41}$.

*   For $328 \div (4 \div 2)$:

    $$
    4 \div 2 = 2
    $$

    $$
    328 \div 2 = 164
    $$
    The second expression equals $\boxed{164}$.

    $$
    6 \div 3 = 2
    $$

    $$
    144 \div 2 = 72
    $$
    The first expression equals $\boxed{72}$.

*   For $(144 \div 6) \div 3$:

    $$
    144 \div 6 = 24
    $$

    $$
    24 \div 3 = 8
    $$
    The second expression equals $\boxed{8}$.

$$
118 \div 4 = 29 \text{ remainder } 2
$$

$$
29 \times 4 + 2 = 116 + 2 = 118
$$
The answer is $\boxed{\text{29 remainder 2}}$.

$$
85 \div 4 = 21 \text{ remainder } 1
$$

$$
21 \times 4 + 1 = 84 + 1 = 85
$$
The answer is $\boxed{\text{21 remainder 1}}$.

$$
261 \div 4 = 65 \text{ remainder } 1
$$

$$
65 \times 4 + 1 = 260 + 1 = 261
$$
The answer is $\boxed{\text{65 remainder 1}}$.

$$
475 \div 9 = 52 \text{ remainder } 7
$$

$$
450 \div 9 = 50
$$
The answer 52 is close to the estimate 50, so it is $\boxed{\text{reasonable}}$.

$$
234 \div 9 = 26
$$

$$
230 \div 9 \approx 25.5
$$
The answer 26 is close to the estimate 25.5, so it is $\boxed{\text{reasonable}}$.

$$
701 \div 9 = 77 \text{ remainder } 8
$$

$$
720 \div 9 = 80
$$
The answer 77 is close to the estimate 80, so it is $\boxed{\text{reasonable}}$.

$$
511 \div 9 = 56 \text{ remainder } 7
$$

$$
540 \div 9 = 60
$$
The answer 56 is close to the estimate 60, so it is $\boxed{\text{reasonable}}$.