solution:
Let the number be ABCDE
>>The second digit is three times the fourth digit<<
So D is 1,2, or 3 and B is 3,6 or 9.
The number is A3C1E, A6C2E, or A9C3E
>>The second digit is ... five more than the fifth digit.<<
That rules out 3 for B, so B is 6 or 9, and D is 2 or 3.
It also tells us that E is 1 or 4, so that B can be 5 more than it.
So the number is A6C21 or A9C34
>>The third digit is ... twice the fourth digit<<
So C is twice D, which is 2 or 3. So C is 4 or 6
So the number is A6421 or A9634
>>The third digit is one-half the first digit
So C is 4 because 6 is too large to be half a digit. And so
A has to be 8 so that C=4 can be half of it.
So the number is 86421.
