Final answer:
The number 2.583 x 10^12 has four significant figures, as all digits in the coefficient 2.583 are significant, and the exponent only locates the decimal point.
Step-by-step explanation:
The number of significant figures in the measurement 2.583 x 10^12 is four. In scientific notation, the coefficient (2.583 in this case) contains all the significant figures, while the exponent (10^12) only serves to locate the decimal point and does not affect the count of significant figures. Therefore, we do not count any digits in the exponent towards the total number of significant figures. By definition, all non-zero digits are considered significant, as well as any zeros between them or after a decimal point. Since 2.583 has no leading or trailing zeros, all four digits are significant.