How Many Significant Figures Are in 0.020?
0.020 has 2 significant figures: the 2 and the final zero after the decimal. See the digit-by-digit rule, scientific notation, and common mistakes.
Digit-by-digit breakdown
Step-by-step explanation
Start at the left and ignore zeros before the first non-zero digit. In 0.020, the first 0 and the 0 immediately after the decimal only locate the decimal place.
The digit 2 is non-zero, so it is always significant.
The final 0 is to the right of a non-zero digit and the number has a decimal point, so that zero is significant too.
That leaves two significant digits: 2 and 0. Therefore, 0.020 has 2 significant figures.
Why this answer is correct
Why the first two zeros do not count
Leading zeros are placeholders. They tell you that the value is two hundredths, but they do not describe measurement precision. If you rewrote 0.020 as 20 x 10^-3, those first zeros would disappear without changing the measured value.
Why the last zero does count
The last zero appears after the 2 and after the decimal point. That means it is not just holding a place; it says the value was reported to the thousandths place. In a measurement, 0.020 is more precise than 0.02 even though both have the same numerical value.
Scientific notation removes the ambiguity
Writing the number as 2.0 x 10^-2 makes the answer obvious. The coefficient is 2.0, and both digits in that coefficient are significant. The exponent changes the scale, not the significant figure count.
Common mistakes to avoid
Counting every zero and saying 0.020 has 4 significant figures.
Dropping the final zero and saying it has only 1 significant figure.
Treating 0.020 and 0.02 as equally precise measurements. They are equal in value, but 0.020 communicates more precision.
Frequently asked questions
Is 0.020 the same as 0.02 for significant figures?
No. They have the same numerical value, but they do not communicate the same precision. 0.02 has 1 significant figure, while 0.020 has 2 significant figures because the final zero after the decimal is significant.
How many decimal places does 0.020 have?
0.020 has 3 decimal places because there are three digits to the right of the decimal point: 0, 2, and 0.
What is 0.020 in scientific notation with sig figs?
0.020 is 2.0 x 10^-2. The coefficient 2.0 shows exactly 2 significant figures.
Why is the zero after 2 significant in 0.020?
A trailing zero after a decimal point is significant when it follows a non-zero digit. It shows the measurement was reported to that decimal place.