Xiao Yuzai, who has always fantasized about getting a lot of money, finally realized a small part of his dream - after years of hard work, he won 4,000 yuan in the lottery. At this moment, Xiao Yuzai was holding two lottery tickets tightly, resisting the urge to look up to the sky and scream, thinking about why it was not 5,000 yuan. He couldn't figure out how to calculate it. However, according to Xiao Yuzai's mind, he really couldn't understand this kind of arithmetic problem. Although he was studying accounting, he really couldn't understand it.