The result should have the same number of significant figures as the measurement with the least significant figures, which is 2.5 (2 significant figures).

In multiplication, the result should have the same number of significant figures as the factor with the least significant figures. 3.00 has 3 significant figures and 2.5 has 2 significant figures, so the answer should have 2 significant figures.

The result should have 2 significant figures, as 2.5 has the least significant figures.

In multiplication, the result should have the same number of significant figures as the factor with the least significant figures. 3.00 has 3 significant figures and 2.5 has 2 significant figures, so the answer should have 2 significant figures.

The result should have 2 significant figures, as 2.5 has the least significant figures.

In multiplication, the result should have the same number of significant figures as the factor with the least significant figures. 3.24 has 3 significant figures and 2.1 has 2 significant figures, so the answer should have 2 significant figures.

Rounding to three significant figures gives 0.00457.

When rounding to three significant figures, 0.6789 becomes 0.679.

In subtraction, the result should be rounded to the least number of decimal places. 100.5 has one decimal place, so 200 - 100.5 = 99.5.

In subtraction, the result should be rounded to the least number of decimal places. 10.0 has one decimal place and 5.678 has three, so the answer should be rounded to one decimal place: 4.32 becomes 4.3.

23.40 has 4 significant figures, while 0.0450 has 3.

25.00 has 4 significant figures due to the trailing zeros.

0.045 has only 2 significant figures.

0.00450 has 3 significant figures due to the trailing zero after the 5.

In scientific notation, all non-zero digits and any trailing zeros after the decimal point are significant. Therefore, 0.0004500 is expressed as 4.500 x 10^-4.

In scientific notation, 0.0004500 is represented as 4.500 x 10^-4, which retains all significant figures (4, 5, 0, 0).

Trailing zeros in a decimal are significant.

2500 has 2 significant figures unless specified with a decimal point.

25.00 has 4 significant figures due to the trailing zeros after the decimal.

The number 100 has only 1 significant figure unless specified otherwise.

0.00560 has 3 significant figures, 0.0560 has 3 significant figures, 0.560 has 3 significant figures, and 5.60 has 3 significant figures. However, 0.00560 is the smallest number, but all have the same count of significant figures.

7.890 x 10^3 has 4 significant figures, while the others have 3, 3, and 4 respectively, but the leading zeros in the first and last options do not count.

0.0300 has three significant figures (the zeros after the 3 are significant because they come after a decimal point).

In the operation 3.00 x 4.0, 3.00 has three significant figures and 4.0 has two. The result will have two significant figures, which is the least among the options.