Approximation Challenge: Estimating 431 to the Nearest Ten or Hundred

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

• Step 1: Identify the tens digit of the number 431.
• Step 2: Apply the rounding rule to the nearest hundred.
• Step 3: Compare with the given choices to select the correct answer.

Now, let's work through each step:
Step 1: The number is 431, and the tens digit is 3 (from the 31 portion).
Step 2: According to rounding rules, since the tens digit (3) is less than 5, we round down. Thus, 431 rounded to the nearest hundred is 400.
Step 3: The choices provided are 500, 400, 440, and 430. The rounded result, 400, matches choice 2.

Therefore, the correct approximation of 431, rounding to the nearest hundred, is $400$.