Rank: ? (1200)
Member #: 12930

ABCD * 4 = DCBA

Find the numbers:
A
B
C
D
. Is there a a general rule for that? What do you do with :

ABCDE * 4 = EDCBA

?

Rank: ? (4)
Member #: 15695

are any of the numbers the same or are they all different?

Rank: ? (1200)
Member #: 12930

All different

Rank: Unregistered

A 2
B 1
C 7
D 8

Rank: ? (4)
Member #: 15695

that was me, not used to this new forum and wasnt logged in

Rank: ? (21)
Member #: 4335

ABCDE * 4 = EDCBA => A=2, B=1, C=9, D=7, E=8;

It does seem to form a pattern--the outter numbers seem to stay the same but you have to figure out the one number inside. Anyways, there are two ways to figure this out:

1. Since A * 4 = E, it means that A = 1 or 2; but since E * 4 mod 10 = A, A has to be an even number, so A is 2. E is either 8 or 9 because of 2 * 4 + whatever comes from B * 4, but since only 8 * 4 can result in a 2 in the unit digit, E = 8. B * 4 < 10 because the next digit is 2 * 4 = 8, which means that B is also 1 or 2, and since (D * 4 + 3) mod 10 = B, B has to be an odd number, so B = 1. D * 4 + 3 = 10 * (something) + 1 => D = 2 or 7; 1 * 4 + whatever from C * 4 = D => D > 4 and thus D = 7. So 7 * 4 + 3 = 31, which means that C * 4 + 3 = (7 - 1 * 4) * 10 + C, solve the equation and C = 9.

2. We are on a programming forum more or less... so here comes the rather easy (& cheesy) way.
Code: