Half price of 4 is 2 yuan, the first 4 yuan and the second 2 yuan, so a * * * spent 6 yuan.

Primary school mathematics is to lay the foundation for students' future mathematics study. It is very important to have a clear understanding of what children have learned, which requires children to make some induction and summary in time. The following are the relevant knowledge points involved in primary school mathematics compiled by People's Education Publishing House, from which students can summarize their knowledge.