How do you determine significant figures in a number?

How do you determine significant figures in a number?

• A. Start with the first non-zero digit, count all subsequent digits, including zeros between non-zero digits.
• B. Count all digits from the left including leading zeros.
• C. Ignore zeros altogether.
• D. Only digits after the decimal point are significant.

Answer: (A)

Significant figures reflect how precisely a value is known, and you determine them by starting at the first nonzero digit and counting every digit to the right, zeros included. Zeros that appear after that first nonzero carry information about precision, so they are part of the count. For example, in 1002 the first nonzero is 1, and the remaining digits are 0, 0, and 2, so all four digits are significant—four significant figures. In a decimal like 0.00320, the first nonzero is 3, and the digits to the right are 2 and 0, giving three significant figures. Leading zeros don’t count because they don’t reflect precision, while zeros after the first nonzero do reflect precision in this counting approach (with decimals, trailing zeros are typically intentional and part of the sig figs; without a decimal point trailing zeros can be ambiguous and may require explicit notation).

Significant figures reflect how precisely a value is known, and you determine them by starting at the first nonzero digit and counting every digit to the right, zeros included. Zeros that appear after that first nonzero carry information about precision, so they are part of the count. For example, in 1002 the first nonzero is 1, and the remaining digits are 0, 0, and 2, so all four digits are significant—four significant figures. In a decimal like 0.00320, the first nonzero is 3, and the digits to the right are 2 and 0, giving three significant figures. Leading zeros don’t count because they don’t reflect precision, while zeros after the first nonzero do reflect precision in this counting approach (with decimals, trailing zeros are typically intentional and part of the sig figs; without a decimal point trailing zeros can be ambiguous and may require explicit notation).