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Your guide: Sir AhmedSays brackets have saved more marks than any calculator.
Type √−1 into your calculator and it says “Math ERROR”. No real number times itself gives a negative, so the calculator gives up.
Negative numbers once got the same treatment — “you can't have −3 mangoes”. Then someone opened a bank account, and −3,000 rupees suddenly made a lot of sense. Mathematicians did the same with √−1: instead of giving up, they gave it a name.
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