Didactic Bytes

[TMBest]

199*256*256+77*256+202

[TechnoDemon]

199*256*256+77*256+202

what r u talking about??
hex consist only 00 - FF = 0 - 255, so it means there's no 256

[CodeX]

There's 256 values you can store though, 1-255 is 255 values and 0 is one more so you have 256. Some abstract number theory:
largest value representable: r^d-1
number of values representable: r^d
where r is the radix/root/base (i.e. 2) and d is the number of digits (i.e. so for a binary byte:
2^8-1 = 255
2^8 = 256
just as with decimal you have
10^3-1 = 999
10^3 = 1000

also looking at the post it looks like TMBest is creating a 3 byte value
0xc74dca
go figure

[TechnoDemon]

from what TMBest wrote, there are several possible results coz he wrote no brackets, i couldn't figure which op to execute first:
199*256*256+77*256+202
=> (199*256) * (256+77) * (256+202)
=> 50944 * 333 * 458
=> 7769673216
is different if brackets move one step to the right:
=> 199 * (256*256) + (77*256) + 202
=> 199 * 65536 + 19712 + 202 'even this can result more possibilities (vb mode = ON)
=> if (199 * 65536) + 19712 + 202 = 13041664 + 19914 = 13061578
=> else 199 * (65536+19712+202) = 199 * 85450 = 17004550
and other possibilities.

CONFUSED ::sighs::
even processor will be confused if there's no operation's priority (i mean 'brackets')

[CodeX]

... did you ever go to school?

[TechnoDemon]

oh...
my bad...

I forgot that multiply op is cumulative ( (a*b)*c=a*(b*c) )
this hacker.org's challenges makes me think to complicated.

Btw, thx for the advise, but i'm an university student and almost got my S.E (Sarjana Ekonomi = Bachelor of Economy in Indonesia). I appreciate it...

[CodeX]

I can see why there's a global recession

[Karian]

I forgot that multiply op is cumulative ( (a*b)*c=a*(b*c) )

I guess you mean it is associative?

[TechnoDemon]

@CodeX
hahahaha... just forget about it, it's a shame

@Karian
that's what i mean... forgive my poor english...

[DragonEgghead]

Python:

Code: Select all

int(''.join("%08d"%int(bin(i)[2:]) for i in [199, 77, 202]),2)

[lortedy]

Convert each number from decimal to binary using "calc.exe":

Code: Select all

		199 = 11000111
		  77 = 1001101
		202 = 11001010

Append a 0 at the beginning of 77's binary value.
Concat the 3 values => 110001110100110111001010
Convert binary to decimal => 13061578

Python:

Code: Select all

def binary2decimal(binaryNumber):
	multiplier = 0
	number = 0
	for el in binaryNumber[::-1 ]:
		number += int( el ) * ( 2**multiplier )
		multiplier += 1
	return number

def decimal2binary(decimalNumber):
	bStr = ''
	if decimalNumber < 0: raise ValueError, "Must be a positive integer."
	if decimalNumber == 0: return '0'
	while decimalNumber > 0:
		bStr = str(decimalNumber % 2) + bStr
		decimalNumber = decimalNumber >> 1
	return bStr

a, b, c = 199, 77, 202
a, b, c = decimal2binary(a), decimal2binary(b), decimal2binary(c)
b = '0'+b # Add a leading 0 to binary value of 77 as it has only 7 bits (not a complete byte)
val = ''
val = a+b+c

print binary2decimal(val)

=> 13061578