Which statement correctly describes a significant-figure rule?

• A. Zeros between two significant figures are significant.
• B. Zeros at the end of a decimal number are significant.
• C. Leading zeros are significant.
• D. Zeros used solely for spacing the decimal point are not significant unless a decimal point is present.

Answer: (B)

Significant figures describe how precise a measurement is, and zeros fit into that based on their position. Zeros at the end of a decimal number are significant because the decimal point shows the exact place to which the measurement was made; those trailing zeros indicate the level of precision. For example, 12.3400 communicates precision to the ten-thousandth place, giving five significant figures. Leading zeros, on the other hand, do not add precision—they simply place the decimal point, as in 0.0045 which has two significant figures. Zeros between nonzero digits are also significant, since they are part of the measured value, like in 205 which has three significant figures. Zeros used solely to position the decimal are not significant unless they accompany a decimal point that reveals the precision.