i got confuded from these question by book simply says read where the scales coincide then if it + add it to ur reading now still confused by what the previous question asked
Normally, when you close the jaws of a vernier calliper or those of a micrometer the scale MUST show a reading of zero.
That's because its obviously measuring nothing.
However, sometimes due to callibration errors or misuse of the equipment when you close the jaws the scale DOESN'T read zero.
Instead the scale will show some value. This value, when the jaws are closed, is the zero-error of your vernier calliper/micrometer.
If you use a vernier calliper with a zero error you must do the following :
measured length as per vernier
MINUS zero error.