Final answer:
The number 50.003 00 has seven significant figures, as all digits in this number contribute to its measurement resolution, including the trailing zeros after the decimal point.
Step-by-step explanation:
The number 50.003 00 has seven significant figures. Significant figures are the digits in a number that carry meaning contributing to its measurement resolution. This includes all non-zero digits, any zeroes between non-zero digits, and any zeroes which are both to the right of the decimal point and to the right of a non-zero digit. In this case, the '5' is non-zero, the three zeroes after the decimal are between non-zero digits, and the last two zeroes are to the right of the decimal point and after a non-zero digit.
Note that in the case of numbers such as 1300, the trailings zeros could potentially be ambiguous, so scientific notation might be used to clarify the intended number of significant figures. But in this case, with 50.003 00, the trailing zeros after the decimal point are all significant.