Math Is Fun Forum

this is seriously the hardest maths/logic puzzle i have every seen and im no dunce when it comes to maths straight As but this one i was working on for 2 hours and no luck at all but am completely certian its possible so id thought id try and search the web and see if i can find a solution there.

the rules are that you need to combine any of the letters below so that each number appears an odd number of times exept for 0 which has to appear an even number of times.

may be a bit hard to understand what i mean but hopefully most people will understand.

also i dont suggest you attempt this if unless you are insanely intelligent or have alot of time on your hand or preferably both as i dont wish to waste peoples time.

a)0,1,2,3,4,5
b)0,1,2,4,7,8
c)0,1,2,3,4,5,9,10,11
d)0,2,3,5,6,12
e)0,1,2,4,7,8,9,10,11,13
f)0,2,3,4,6,9,11,12
g)3,5,6,11,12,14
h)1,4,7,8,15,16
i)1,4,7,8,10,13,15,16,23
j)2,4,5,9,10,11,17,18,19
k)2,4,8,9,10,17,19,20
l)2,5,6,9,11,14,17,18,21
m)3,5,6,12
n)4,8,10,13,16,19,20,22,23
o)5,6,11,14,18,21
p)7,8,15,16
q)7,8,13,15,16,23
r)9,10,11,17,,18,19,24,25,26
s)9,11,14,17,18,21,25,26,27
t)9,10,13,17,19,20,24,26,28
u)10,13,19,20,22,23,24,28,29
v)11,14,18,21,25,27
w)13,20,22,23,28,29
x)8,13,16,20,22,23
y)17,19,20,24,26,28,30,31,32
z)17,18,21,25,26,27,30,33,34
A)17,18,19,24,25,26,30,33                      yes it keeps going
B)18,21,25,27,33,34
C)19,20,22,24,28,29,31,32,35
D)20,22,28,29,31,35
E)24,25,26,30,32,33
F)24,28,29,31,32,35
G)24,26,28,29,30,31,32
H)25,26,27,28,30,33
I)25,27,33,34
J)28,29,31,35

like i said insanely hard but althought there are alot of letters to choose from 36 in total it may (enthasis on the may) not be as difficult as it looks as only letter need only be used once twice and it would effectively cancle itself out and just to help a few people heres i few things i noticed which may help

tips
most letters will never be used so dont be intimidated by the number its just a large selection to choose from thats all
start with high or low numbers then work your way up or down
theres alot of combinations for the higher numbers in the letters that can quickly get rid of a large portion of the numbers quickly q,z C seem to get rid of alot using just 3

if any one can complete this i will be massively surprised but very pleased i will post the answer to this as soon as i get it (if i ever get it)