1, three twos add and subtract to get 24. 2, a well 10 meter, a frog jumped 3 meters and fell back 2 meters. How many times can it jump? 3. 10 candles were lit in the room, and three of them were blown out by the cup wind. How many candles were there the next morning? And so on, can not only improve children's interest in learning mathematics, but also help to improve IQ.