Find a six-digit number
We put 6 blanks for the 6 digits:
_ _ _ _ _ _
the second digit is eight more than the first,
Since the first digit can't be 0, then in order for there to be a
digit which is 8 more than the first, the first digit is 1 and
the second digit is 9. So we have:
1 9 _ _ _ _
(the second digit is) one more than the fourth,
So the fourth digit must be 8, so that 9 will be one more than it.
So we have:
1 9 _ 8 _ _
and (the second digit is) two more than the last.
So the last digit must be 7, so that 9 will be two more than it.
So we have:
1 9 _ 8 _ 7
in which the first digit is one less than the third,
So the third digit is 2. So we have
1 9 2 8 _ 7
the third digit is one less than the fifth,
So the fifth digit is 3. So we have the entire number.
1 9 2 8 3 7
and The sum of the first and fourth digits equals the second digit,
That's true, 1+8=9, but we didn't need to know that.
the sum of the first and third digits equals the fifth,
That's true too, 1+2=3, but we didn't need to know that either.
and the sum of all the digits is 30.
That's also true, 1+9+2+8+3+7=30, but we didn't need to know that either.
Edwin