Find the Predecessor: Determining the Number Before 31,440

To find the number that comes before $31,440$, we need to calculate the predecessor using subtraction. Let's go through the steps:

• Step 1: Identify the given information. We have the number $31,440$.
• Step 2: Determine the predecessor by subtracting 1 from the given number. Use the formula: $\text{Predecessor} = n - 1$.
• Step 3: Perform the calculation: $31,440 - 1 = 31,439$.

Thus, $31,439$ is the number that comes before $31,440$.

Therefore, the correct answer is $31,439$.