Plus challenge game let you calculate the result and if you answer correctly, you get score. You can select a number of challenges you need to play or play endlessly until you give wrong answer. The difficulty can be 'easy' , 'medium' or 'hard'
Level easy : the possible operands are 0 - 9 Level medium : the possible operands are 0 - 99 Level hard : the possible operands are 0 - 999
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