BlueHens
Algebrarbegia [100 pts]
Writeup author: lolmenow
Provided files: N/A
78! - k = k - !87 Solve for k flag format is udctf{k}
This is a pretty simple algebra challenge. You need to rearrange the equation so that the subfactorials and the factorials are on the same side, and so is the variable k on the side.
Then, grab the values of factorial 78 and subfactorial 87 (google does just fine)
Divide the entire sum of the processes above by 2 and you get the flag.
Process:
a = 11324281178206297831457521158732046228731749579488251990048962825668835325234200766245086213177344000000000000000000
b = 775400577052889667046640780055684375763111543171042155757864819229947211564419831641783864807987394389543160788597793657791613938734
# got these values from dcode
answer = (a+b) // 2
print(answer)
#answer: 387700288526444839185460979130991103610316350951544192244807199359099600806691328655309595021094080317314686982970896828895806969367
Final flag: udctf{387700288526444839185460979130991103610316350951544192244807199359099600806691328655309595021094080317314686982970896828895806969367}