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This is the case of redundancy or the repeated data. It means that the same data is being repeated again and again. And its the wastage of time and memory both. The redundancy must be removed in all circumstances. However, we cannot as without it proper normalization of data is not possible.

Explanation:

The answer is self explanatory.

you can not change you age soon as you signed up. the only way is too delete your account and use another account to sign up and put your correct age.