Puzzle for September 19, 2022  ( )

Scratchpad

Find the 6-digit number ABCDEF by solving the following equations:

eq.1) A + B + C + D + E + F = 30 eq.2) F = B + D eq.3) A = C + D eq.4) F = A + E eq.5) E - C = C - D eq.6) E - D = C + D

A, B, C, D, E, and F each represent a one-digit non-negative integer.

Scratchpad

 

Help Area

Hint #1


Add D to both sides of eq.6: E - D + D = C + D + D which becomes eq.6a) E = C + 2×D


  

Hint #2


In eq.5, replace E with C + 2×D (from eq.6a): C + 2×D - C = C - D which becomes 2×D = C - D Add D to both sides of the above equation: 2×D + D = C - D + D which makes 3×D = C


  

Hint #3


In eq.6a, replace C with 3×D: E = 3×D + 2×D which makes E = 5×D


  

Hint #4


In eq.3, replace C with 3×D: A = 3×D + D which makes A = 4×D


  

Hint #5


In eq.4, substitute 4×D for A, and 5×D for E: F = 4×D + 5×D which makes F = 9×D


  

Hint #6


Substitute 9×D for F in eq.2: 9×D = B + D Subtract D from each side of the equation above: 9×D - D = B + D - D which makes 8×D = B


  

Solution

Substitute 4×D for A, 8×D for B, 3×D for C, 5×D for E, and 9×D for F in eq.1: 4×D + 8×D + 3×D + D + 5×D + 9×D = 30 which simplifies to 30×D = 30 Divide both sides of the above equation by 30: 30×D ÷ 30 = 30 ÷ 30 which means D = 1 making A = 4×D = 4 × 1 = 4 B = 8×D = 8 × 1 = 8 C = 3×D = 3 × 1 = 3 E = 5×D = 5 × 1 = 5 F = 9×D = 9 × 1 = 9 and ABCDEF = 483159