हाउ टू फाइंड वेदर ए नंबर इज अ परफेक्ट स्क्वेयर ओर नॉट​


हाउ टू फाइंड वेदर ए नंबर इज अ परफेक्ट स्क्वेयर ओर नॉट​

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Katherine 2 weeks 2021-11-23T02:05:09+00:00 1 Answer 0 views 0

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    Step-by-step explanation:

    Digital roots are 1, 4, 7 or 9. No number can be a perfect square unless its digital root is 1, 4, 7, or 9. You might already be familiar with computing digital roots. (To find digital root of a number, add all its digits. If this sum is more than 9, add the digits of this sum. The single digit obtained at the end is the digital root of the number.)

    If unit digit ends in 5, ten’s digit is always 2.

    If it ends in 6, ten’s digit is always odd (1, 3, 5, 7, and 9) otherwise it is always even. That is if it ends in 1, 4, and 9 the ten’s digit is always even (2, 4, 6, 8, 0).

    If a number is divisible by 4, its square leaves a remainder 0 when divided by 8.

    Square of even number not divisible by 4 leaves remainder 4 while square of an odd number always leaves remainder 1 when divided by 8.

    Total numbers of prime factors of a perfect square are always odd.

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18:9+8+9*3-7:3-1*13 = ? ( )