One of my child's Maths teacher told us this. If you keep saying to your child "Why are you so careless ?", he will only remember the word "careless". You should be saying, "Be more careful next time" more often than using the word "careless", then he / she will remember to be careful.

I think a few careless mistakes are fine. Then there will be room for improvement. Even as adults, we can be careless at times. You should be more alarmed if you find that your child is not understanding the question or concept or not knowing where to start solving the problem.

The number of careless mistakes tend to decrease as they grow older. If I can categorize the careless mistakes, I think they normally fall under