Addition Problem: Calculate 31 + 50 Units

To solve this problem, we'll perform simple addition:
Step 1: Identify the numbers to be added, which are 31 and 50.
Step 2: Calculate the sum: $31 + 50$.

Let's perform the calculation:

• Start the addition from the rightmost digit (units place).
• In the units place, add 1 (from 31) and 0 (from 50), giving us 1.
• In the tens place, add 3 (from 31) and 5 (from 50), which gives us 8.

Since there's nothing to carry over, the sum directly gives us the resulting number. Thus, $31 + 50 = 81$.

Therefore, the resulting number when adding fifty units to the number 31 is $81$.