Personally, I think it is better to decompose it first, which can develop children's thinking mode. In fact, it doesn't matter to add and subtract first, and then decompose and understand, but it's too old-fashioned, because everyone has been influenced or benefited by this mode of thinking all his life. We adults think this is relatively micro-innovative. When children grow up, everyone doesn't know the decomposition and addition and subtraction within 10, but when they encounter problems in work and study, they will analyze them backwards. In other words, it is better to decompose first and then add and subtract, and then listen to the results considered by most people's thinking of adding, subtracting and decomposing, which seems to have great significance to people's life. I think it's better to decompose it first, and it must be decomposed first, right?