19 19 years of good friends. 2828, hand in hand. Three seven three seven. Too close. Let's go together, four, four, six, six. Make a pair of hands in half. According to the website of Grade Three, the word "divide" in "divide and merge" means separation. For example, "3" can be divided into "1" and "2", and "combination" means synthesis. For example, "1" and "2" can be combined into "3", and each number has a division and merge.