Positive zero error is when the jaws are closed and the zero on the vernier scale is to the right of the zero of the main scale.The measurement taken with this pair of vernier calipers will be MORE than the actual result. To get the correct value, the zero error must be subtracted from each reading. Eg: The zero error (0.03) is subtracted from the reading. The actual reading is thus (eg) 2.35-0.03cm= 2.32

Negative error is when the jaws and closed and the zero of the vernier scale is to the left or the zero of the main scale. The measurement taken with this pair if vernier calipers will be LESS than the actual value. To get the correct value, the numerical value of the zero error must be ADDED to each reading. Eg: The 4th line on the vernier scale is in line with the marking on the main scale. The zero error (0.10-0.04cm=0.06cm) is added to the rading. The actual reading is thus 2.35+0.06cm=2.41

Negative error is when the jaws and closed and the zero of the vernier scale is to the left or the zero of the main scale. The measurement taken with this pair if vernier calipers will be LESS than the actual value. To get the correct value, the numerical value of the zero error must be ADDED to each reading. Eg: The 4th line on the vernier scale is in line with the marking on the main scale. The zero error (0.10-0.04cm=0.06cm) is added to the rading. The actual reading is thus 2.35+0.06cm=2.41