Heuristics decision-making is the path, the shortcut of the human mind in making an immediate decision on the process of problem-solving in abstract algebra proofing. Heuristics decision-making are classified into four components, i.e. representative, availability, adjustment and anchoring. This study combined a quantitative and qualitative approach. A test was done twice in order to measure the five stages of verification, and questionnaires were also used to measure heuristics decision and

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... e analyzed descriptively. The results of this study were (1) the students having representative heuristics were able to write the verification well; those having availability heuristics were able to prove when they were given the similar example with the problem; those having adjustment heuristics were able to prove with the ideas and concepts that have been understood; and those having anchoring heuristics cannot control the mistakes made in symbols writing, key ideas, steps, conditions of proof, and reasons supporting theorem; and (2) from the interview, it was revealed that the proof can be done if there are similar examples and with the help of friends, the students did not have a fully learning independence, the students were less confidence in making heuristics decision.