Solve Vertical Addition: 378 + 455 Step-by-Step

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

• Step 1: Align the numbers vertically by place value, which are the units, tens, and hundreds places.
• Step 2: Begin adding from the far right (units place), moving left.
• Step 3: Regroup if a column sum is 10 or greater.

Now, let's work through each step:

Step 1: Align numbers:

$\begin{aligned} & \phantom{0}378 \\ + & \\ & \phantom{0}455 \\ \end{aligned}$

Step 2: Begin with the units place:
8 (units from 378) + 5 (units from 455) = 13.
Write down 3 in the units place, and carry over 1 to the tens place.

Step 3: Move to the tens place:
7 (tens from 378) + 5 (tens from 455) + 1 (carried over) = 13.
Write down 3 in the tens place, and carry over 1 to the hundreds place.

Step 4: Finally, add the hundreds place:
3 (hundreds from 378) + 4 (hundreds from 455) + 1 (carried over) = 8.
Write down 8 in the hundreds place.

The final sum is, therefore:

$\begin{aligned} & \phantom{0}378 \\ + & \\ & \phantom{0}455 \\ \hline & \phantom{0}833 \end{aligned}$

Therefore, the solution to the problem is $833$.