Solve Three-Digit Addition: 685 + 315 in Vertical Format

$\begin{aligned} &685 \\ +& \\ &315 \\ &\underline{\phantom{776}} & \\ \end{aligned}$

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

• Step 1: Add the units column
• Step 2: Add the tens column, including any carry from the units
• Step 3: Add the hundreds column, including any carry from the tens

Now, let's work through each step:

Step 1: Add the units column.

The units are $5$ (from $685$) and $5$ (from $315$).
$5 + 5 = 10$. Write $0$ in the units place and carry over $1$ to the tens place.

Step 2: Add the tens column, including any carry from the units.

The tens are $8$ (from $685$) and $1$ (from $315$), plus the $1$ carried over.
$8 + 1 + 1 = 10$. Write $0$ in the tens place and carry over $1$ to the hundreds place.

Step 3: Add the hundreds column, including any carry from the tens.

The hundreds are $6$ (from $685$) and $3$ (from $315$), plus the $1$ carried over.
$6 + 3 + 1 = 10$. Write $0$ in the hundreds place and $1$ in the thousands place.

Therefore, the solution to the problem is $1000$.