CBSE Class 11-science Answered

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At least one digit being repeated, so we are EXCLUDING distict 4 digit numbers.

To find total numbers with repeatation of digits,

first digit can be selected in out of four, i.e. 1,2,5,7 in 4 different ways,

Similarly for second, third and fourth,

Total numbers possible = 4x4x4x4 = 256.

Number of numbers with distinct 4 digits, = 4! = 24

The required numbers are = 256 - 24 = 232

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