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Solution

1. Step 1Convert hex to decimal with Python
   0x3D breaks down as 3*16 + 13 = 61. Python's int() with base 16 converts hex strings directly: int('0x3D', 16) returns 61.
   python3 -c "print(int('0x3D', 16))"Copied!
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   Hexadecimal (base 16) is the number system most commonly used in computing and security. It uses sixteen digits: 0-9 for values 0-9, and A-F (or a-f) for values 10-15. The prefix 0x is the conventional way to indicate a hexadecimal number in source code and shell environments.

   Converting hex to decimal manually: multiply each digit by its positional power of 16 and sum the results. For 0x3D: the digit 3 is in the 16's place (3 × 16 = 48), and the digit D (= 13) is in the 1's place (13 × 1 = 13). Sum: 48 + 13 = 61.

   Why hexadecimal matters in security:

   • Each hex digit represents exactly 4 bits (a nibble), so 2 hex digits = 1 byte
   • Memory addresses, opcodes, file offsets, and color codes are all conventionally written in hex
   • Hash values (MD5, SHA-256) and cryptographic keys are displayed as hex strings
   • Network packets and binary file formats are analyzed in hex editors

   Python's int(x, base) function converts any string to an integer in the given base. Similarly, hex(n) converts an integer to its hex string, bin(n) gives binary, and oct(n) gives octal. For quick conversions in the shell, printf '%d\n' 0x3D or echo $((16#3D)) both work without Python.

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0x3D = 3*16 + 13 = 61. Python's int(x, 16) converts hex strings to decimal.