Final answer:
To determine which number is greater between 10.042 and 10.0421, we compare each digit by place value and find that 10.0421 is greater because it has an additional non-zero digit.
Step-by-step explanation:
The question asks which number is greater between 10.042 and 10.0421. To compare these two decimal numbers, we look at their place values. Starting from the left, the digits 10 are the same in both numbers. Moving to the right, the next digit after the decimal point is a 0 in both numbers, so they are still equal. Continuing, the next digits are 4 in both numbers, so they remain equal. After that, the second place after the decimal is a 2 in both numbers, which are still equal. However, the next place is where they differ; the first number has no digit (which is effectively 0), while the second number has a 1.
Since 1 is greater than 0, 10.0421 is the greater number. Therefore, the answer is b) 10.0421.