🔍 Key Concepts

• Micrometer structure: The reading is the sum of the sleeve (barrel) reading plus the thimble reading. • Inch micrometer graduations: On a standard inch micrometer, each numbered line on the sleeve is 0.100", and each short line is 0.025". • Thimble scale: Each division on the rotating thimble usually equals 0.001"; 25 divisions make one full 0.025" turn.

💭 Think About

• First, figure out what combination of 0.100", 0.025", and 0.001" marks will add up to 0.438". • Then, for each figure, read the sleeve value just to the left of the thimble edge, and add the thimble value that lines up with the horizontal reference line. • Compare your calculated value for each candidate figure to 0.438" and eliminate those that are obviously too small or too large.

✅ Before You Answer

• Be sure the sleeve reading includes all visible 0.100" and 0.025" marks to the left of the thimble edge. • Confirm which thimble graduation line exactly coincides with the sleeve’s reference line; multiply that number by 0.001". • Double‑check that your final sum is 0.438", not 0.428" or 0.448"—small mistakes of 0.010" are easy to make.