Question

Round the following to the indicated number of significant figures:

(a) 0.424 (to two significant figures)

(b) 0.0038661 (to three significant figures)

(c) 421.25 (to four significant figures)

(d) 28,683.5 (to five significant figures)

Short answer

a) 0.424 rounds down to 0.42.

b) 0.0038661 rounds up to 0.00387.

c) 421.25 rounds down to 421.2.

d) 28,683.5 rounds up to 28,684.

Step-by-step solution

Significant figures

All the digits in measurement, including the uncertain last digit, are called significant figures or significant digits.

Rules used to determine the significant figures in a number

• Non-zero digits are always significant.
• Any zero between two significant digits is significant.

a) 0.424 rounds "down" to 0.42 (The removed digit, 4, is less than 5).

b) 0.0038661 rounds "up" to 0.00387 (The removed digit, 6, and the retained digit are odd).

c) 421.25 rounds "down" to 421.2 (The removed digit, 5, and the retained digit are even).