Section A - Multiple Choice. Instruction: Attempt all questions in this section. What is the place value of 6 in the number 486312?

The number is 48631. The digit whose place value is required is 6.

In the number 48631, we identify the place value of each digit from right to left:

• The digit 1 is in the units place ($10^0$).
• The digit 3 is in the tens place ($10^1$).
• The digit 6 is in the hundreds place ($10^2$).
• The digit 8 is in the thousands place ($10^3$).
• The digit 4 is in the ten thousands place ($10^4$).

Since the digit 6 is in the hundreds place, its place value is 6 multiplied by 100.

Comparing this with the given options:
A. 600
B. 60
C. 6000
D. 0.6

The calculated place value matches option A.

The final answer is $\boxed{\text{A. } 600}$.