A number with 100 digits is given. The first two digits of that number are 2 and 9.
How many digits has a square of that numb

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A number with 100 digits is given. The first two digits of that number are 2 and 9.
How many digits has a square of that number?​

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2 thoughts on “A number with 100 digits is given. The first two digits of that number are 2 and 9.<br />How many digits has a square of that numb”

  1. Step-by-step explanation:

    Given:

    A number with 100 digits is given. The first two digits of that number are 2 and 9.

    To find:

    How many digits has a square of that number?

    Solution:

    Number of digits in the given number = 100

    The first two digits in the number = 2 and 9

    Wr know that

    The number of digits in the square of a number with one digit (from 1-9) = 1 or 2

    since 1^2=1 and 9^2=81

    The number of digits in the square of a number with two digits (from 10-99)= 3 or 4

    Since 10^2 = 100 and 99^2 = 9801

    The number of digits in the square of a number with three digits (from 100-999)= 4 or 5

    If we continue like this we get the following general formula:

    1 or 2 can be written as 2(1)-1 or 2(1)

    3 or 4 can be written as 2(2)-1 or 2(2)

    5 or 6 can be written as 2(3)-1 or 2(3)

    .

    .

    .

    The number of digits in the square of a number with n digits =2n-1 or 2n

    So ,

    The number of digits in the square of a number with 100 digits =

    2(100)-1 or 2(100)

    =>200-1 or 200

    =>199 or 200

    If it has 2 in its units place it has 199 digits in the square of the number.

    If it has 9 in its units place it has 200 digits in the square of the number.

    Answer:

    The number of digits in the square of a number with 100 digits = 199 or 200

    1)If it has 2 in its units place it has 199 digits in the square of the number.

    (The first two digits like 29)

    2)If it has 9 in its units place it has 200 digits in the square of the number.

    (The first two digits like 92)

    Used formulae:

    • The number of digits in the square of a number with n digits =2n-1 or 2n
    Reply
  2. Given : a number with 100 digits

    The first two digits of that number are 2 and 9

    To Find : How many digits has a square of that number

    29yyyy________

    Hence its less than

    300000_________

    3 with 99 0’s

    and greater than

    2000000_______

    2 with 99 0’s

    Square of 3 with 99 0’s will be

    9000000_______

    9 with 198 0’s

    Hence 199 digits

    Square of 2 with 99 0’s will be

    4000000_______

    4 with 198 0’s

    Hence 199 digits

    Hence square of that number

    is greater than a number of 199 digits also lesser than a number of 199 digits

    Hence number must be of 199 digits

    so square of that number will have 199 Digits

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