Mr Zhang, who was working outside, did not find his employer and bought a return ticket with 1 yuan left. He bought crayons and 4 cigarette boxes, cut them into 24 cards, and raised them at the exit of the station. Holding a "rental pick-up sign (2 yuan)". As a result, many people rented his pick-up sign. Soon he earned 40 yuan. One month later, he made 40 pieces of galvanized sheets. The "welcome card" can earn 200 yuan a day. After 3 months, he rented a house and had a helper. Later, he used the 30,000 yuan earned by renting the "welcome card" to open a flower shop and contract. The flower wholesale business. In this way, he turned 1 yuan into 1 million yuan in 1 year. What does this text mainly tell us? ['Creating wealth is a science and an art.', 'Opportunities always favor those who are intelligent and intelligent.', 'Whoever turns quickly and uses it flexibly, whoever is "golden".', 'As long as you are good at using knowledge, wisdom and hard work, small money will become a big money.']