Solve Vertical Addition: 40 + 3 Step by Step

$\begin{aligned} &40 \\ +& \\ &~~3 \\ &\underline{\phantom{776}} & \\ \end{aligned}$

To solve this problem, we'll perform vertical addition of the numbers 40 and 3:

• Step 1: Write the numbers vertically, aligning by place value:
  $\begin{array}{c} 40 \\ + 3 \\ \hline \end{array}$
• Step 2: Start adding from the rightmost column (units place).
  Units column: 0 + 3 = 3, write this number directly below the line.
  $\begin{array}{c} 40 \\ + 3 \\ \hline 43 \\ \end{array}$
• Step 3: Move to the next column (tens place):
  In the tens place: 4 + 0 = 4, write this number below the line in the tens place.

As a final result, the sum of 40 and 3 is 43.

Therefore, the solution to the problem is $43$, which matches choice number 4 in the provided options.