Craig measured a length as 0.034 millimeters. What is the margin of error?

Craig’s measurement, 0.034 mm, is recorded to the nearest 0.001 mm. The margin of error is half of that smallest unit, or 0.0005 mm, so the actual length is from 0.034 − 0.0005 = 0.0335 mm to 0.034 + 0.0005 = 0.0345 mm. This matches the range 0.0335 mm to 0.0345 mm.

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