Solve Vertical Subtraction: 118 minus 9

To solve this problem, we'll follow these steps:

• Step 1: Set up the subtraction problem vertically, aligning the digits by place value.
• Step 2: Begin with the units place.
• Step 3: Consider any necessary borrowing from the higher place value.
• Step 4: Complete the subtraction in all place values.

Now, let's work through each step:

Step 1: Align the numbers vertically as follows:

$\begin{array}{c} 1 & 1 & 8 \\ - & & 9 \\ \hline \end{array}$

Step 2: Start from the units column. Here we have $8$ (minuend) and $9$ (subtrahend). Since $8$ is less than $9$, we cannot directly subtract.

Step 3: Borrow 1 from the tens place of $118$ which makes the tens place $0$, and the $8$ in the units place becomes $18$.

Step 4: Compute $18 - 9 = 9$. Place the result under the units column.

Step 5: In the tens column, now we have $0 - 0 = 0$ since after borrowing, the tens of $118$ are reduced.

Step 6: In the hundreds column, copy the $1$ as there is no subtraction required here.

The final subtraction will look like this:

$\begin{array}{c} 1 & 0 & 18 \\ - & & 9 \\ \hline 1 & 0 & 9 \\ \end{array}$

The answer to $118 - 9$ is $\textbf{109}$.

Therefore, the solution to the subtraction problem is $109$.