If there are careless errors you repeatedly make, consider noting them down. Whether it's an formula you keep recalling incorrectly or a decimal error you often make when converting to a percentage, actively make an effort to not let it happen again.
Perhaps, for example, you keep forgetting that "2" is a prime number or that a non-positive number can include the integer "0". Write them down and look at that list now and again so you don't forget!
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