What is absolute errors?

The difference in value between an approximation and the actual value is called absolute error.

If the actual value is greater than the approximation.Then,
Absolute error = actual value - approximation
E.g if actual value is 503 ,approximation is 50
503-500，absolute error is 3.

Also, If the actual value is smaller than approximation ,then
Absolute error=approximation-actual value
E.g length of ribbon=10.4(cor.to the nearest 0.1cm)
Absolute error=10.4-10.35
(10.35 is the ribbon length)

Also it have maximum absolute error
1/2 x correct to nearest of the measuring
E.g 1/2 x 0.5 cm.

Hope I can help you solve the problems.