Operate four random integers [1..13] with +,-,*,/ operators so that the end of result is 24. Features with displaying the problem difficulty, timer, providing one of answers.
史努比过山车
另一面方块
秦时乱世
机器人车变形
宝宝记忆锻炼
鱼食恐慌!
佩奇的冒险之旅
欧洲火车2019