Solve Vertical Addition: 631 + 9 Step by Step

$\begin{aligned} &631 \\ +& \\ &~~~~9 \\ &\underline{\phantom{776}} & \\ \end{aligned}$

To solve this problem, we'll perform vertical addition for the numbers 631 and 9, handling any necessary carrying.

Align the numbers based on their place value:

$\begin{aligned} &631 \\ +& \\ &~~~9 \\ \end{aligned}$

• Step 1: Add the units place (rightmost column).
  - We have 1 (from 631) + 9 = 10.
  - Write 0 and carry over 1 to the tens place.
• Step 2: Add the tens place (second column from the right).
  - We have 3 (from 31) + 0 + 1 (carry-over) = 4.
  - Write 4 in the tens place.
• Step 3: Add the hundreds place (leftmost column).
  - We have 6 only (as there’s nothing else to add).
  - Write 6 in the hundreds place.

Thus, the final sum of 631 and 9 is 640.

Therefore, the solution to the problem is $\textbf{640}$.