Here are the calculations using long division: 1. Using long division. Calculate the following a) $264 \div 12$ Step 1: Divide 26 by 12. $$ \begin{array}{r} 2 \\ 12 \overline{) 264} \\ -24 \downarrow \\ \hline 2 \end{array} $$ Step 2: Bring down the 4 to make 24. Divide 24 by 12. $$ \begin{array}{r} 22 \\ 12 \overline{) 264} \\ -24 \downarrow \\ \hline 24 \\ -24 \\ \hline 0 \end{array} $$ The remainder is 0. Answer: $\boxed{\text{22}}$ b) $396 \div 18$ Step 1: Divide 39 by 18. $$ \begin{array}{r} 2 \\ 18 \overline{) 396} \\ -36 \downarrow \\ \hline 3 \end{array} $$ Step 2: Bring down the 6 to make 36. Divide 36 by 18. $$ \begin{array}{r} 22 \\ 18 \overline{) 396} \\ -36 \downarrow \\ \hline 36 \\ -36 \\ \hline 0 \end{array} $$ The remainder is 0. Answer: $\boxed{\text{22}}$ c) $455 \div 27$ Step 1: Divide 45 by 27. $$ \begin{array}{r} 1 \\ 27 \overline{) 455} \\ -27 \downarrow \\ \hline 18 \end{array} $$ Step 2: Bring down the 5 to make 185. Divide 185 by 27. $$ \begin{array}{r} 16 \\ 27 \overline{) 455} \\ -27 \downarrow \\ \hline 185 \\ -162 \\ \hline 23 \end{array} $$ The remainder is 23. Answer: $\boxed{\text{16 remainder 23}}$ d) $672 \div 21$ Step 1: Divide 67 by 21. $$ \begin{array}{r} 3 \\ 21 \overline{) 672} \\ -63 \downarrow \\ \hline 4 \end{array} $$ Step 2: Bring down the 2 to make 42. Divide 42 by 21. $$ \begin{array}{r} 32 \\ 21 \overline{) 672} \\ -63 \downarrow \\ \hline 42 \\ -42 \\ \hline 0 \end{array} $$ The remainder is 0. Answer: $\boxed{\text{32}}$ 2. Fill in the missing number, Show Calculation a) $\_ \div 25 = 12$ Step 1: Let the missing number be $x$. $$ \frac{x}{25} = 12 $$ Step 2: To find $x$, multiply both sides by 25. $$ x = 12 \times 25 $$ Step 3: Perform the multiplication. $$ x = 300 $$ Answer: $\boxed{\text{300}}$ That's 2 down. 3 left today — send the next one.