What is the precision of the number 123.123456?

The precision of a numerical value refers to the number of digits that are used in the representation of that number, particularly in terms of significant figures. In the case of the number 123.123456, it contains a total of 9 digits: three before the decimal point (1, 2, and 3) and six after the decimal point (1, 2, 3, 4, 5, and 6).

When calculating precision, all non-zero digits are considered significant, as well as any zeros that occur between significant digits. Thus, for 123.123456, all the digits contribute to the precision.

Therefore, the precision is determined to be 9, because the total count of the significant digits in the number is indeed nine. This is why the correct answer is indicated as 9.