2Warm

Description

Solution

1. Step 1Convert decimal to binary with Python
   Open a Python shell and call bin(42). Python returns '0b101010' -- the '0b' prefix signals binary notation and is not part of the answer. Strip it off: the flag is 101010.
   python3 -c "print(bin(42))"Copied!
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   Binary (base 2) is the numeral system used internally by every digital computer. Each digit, called a bit, can only be 0 or 1, corresponding to off and on states in electronic circuits. Groups of 8 bits form a byte, the fundamental unit of data storage and transmission.

   Converting from decimal to binary is done by repeatedly dividing by 2 and recording remainders. For 42: 42 ÷ 2 = 21 R0, 21 ÷ 2 = 10 R1, 10 ÷ 2 = 5 R0, 5 ÷ 2 = 2 R1, 2 ÷ 2 = 1 R0, 1 ÷ 2 = 0 R1. Reading the remainders from bottom to top gives 101010. Python's bin() automates this and prepends 0b to signal the base.

   Knowing how to convert between number bases is essential in CTF and security work. Hexadecimal (base 16) is used for memory addresses and color codes. Octal (base 8) appears in Unix file permissions. Binary shows up directly in bitwise operations, network subnetting, and binary exploitation.

   • bin(n) -- decimal to binary string in Python
   • hex(n) -- decimal to hex string in Python
   • oct(n) -- decimal to octal string in Python
   • int('101010', 2) -- binary string back to decimal

Flag

picoCTF{...}

Binary is base-2 -- each digit is a power of 2. Python's bin() function shows a '0b' prefix which is not part of the answer.