Question

In a six-digit number, the sixth, that is, the rightmost, digit is the sum of the first three digits, the fifth digit is the sum of first two digits, the third digit is equal to the first digit, the second digit is twice the first digit and the fourth digit is the sum of fifth and sixth digits. Then, the largest possible value of the fourth digit is

• A. 8
• B. 7
• C. 9
• D. 4

Answer 1

Answer: (B)

7

Answer 2

Let the number be represented as ABCDEF, where A, B, C, D, E, and F are the digits.

Given the conditions:
$C=A$
$B=2A$
$F=A+B+C=A+2A+A=4A$
$E=A+B=A+2A=3A$
$D=E+F=3A+4A=7A$
Since A and D are both digits, the maximum possible value of A is 1. Therefore, the maximum value of D is 7.