Error Pattern of Whole Number Subtraction in the 3rd Graders of Elementary School

The objective of research was to find error pattern and cause in Whole Number counting operation in the 3 graders of Elementary School. To reveal the pattern and cause of error in Whole Number subtraction operation in the 3 graders of Elementary school, the author employed qualitative approach with action research design that was collaborative in nature. This research was taken place in the 3 grade of Public Elementary School 2 of Panjer, Kebumen Sub District. The subject of research consisted of 40 (forty) 3 graders of Elementary School. From the result of research, it could be found that: error pattern of whole number subtraction operation made by the 3 graders of Elementary School included: (a) reading and writing number, (b) writing number symbol, (c) subtraction concept, (d) ones, tens, hundreds, thousands numbers are subtracted with ones number, (e) incomplete algorithm, (f) random error, (g) place value, (h) basic fact, (i) large number subtracted with small number, (j) error form of 0 a = 0, (k) error form of a b = 0, if a < b, and (l) forgetting to subtract the figure after it