This paper presents our research on Indonesian question answering system for solving arithmetic word problems using pattern matching approach on intelligent humanoid robot. The objective of this paper is to elaborate how natural language processing (NLP) and pattern matching approach works in question answering system for solving arithmetic word problems. Upon receiving a Indonesian arithmetic word problem, the robot will translate Indonesian speech to English text, resolve conjunction problem, co-references problem, question preprocessing, question analysis, represent the knowledge, and lastly the robot will answer the solution. We employed NLP for English by using Natural Language Toolkit (NLTK) in our research. Based on the experiment results, it can be concluded that: (i) the accuracy of the question answering system for each scheme ranges from 80% to 100% depend on the difficulty to comprehend the word problem, (ii) the response time is rather slow with average processing time is about 1.12 minutes.