What 5-digit number satisfies the following requirements?
1. No zeroes
2. First two digits are the same
3. Fourth digit is twice the first
4. Last digit is twice the third
5. Sum of all digits is 18
There are several ways of solving this. One way is to represent each spot with a letter, A – E.
Then you have these equations:
A = B
D = 2 * A
E = 2 * C
A + B + C + D + E = 18
By simplifying, you get:
4 * A + 3 * C = 18
Plug in values for A and C to find that A = 3 C = 2.