Addition & Subtraction. Solved. From the innovators who bring you Times Tables Rock Stars, comes a highly engaging platform for learning to add and subtract… NumBots! NumBots is all about every child achieving the “triple win” of understanding, recall and fluency in mental addition and subtraction, so that they move from counting to calculating. Suitable from Year 1 (UK) or Kindergarten (US) upwards. Younger players will be able to access the early stages from a mathematical point of view but will find it increasingly harder to reach the level of fluency required to make progress.