Puzzle for August 17, 2019  ( )

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

eq.1) A + B + C + D + E + F = 32 eq.2) D + F = A + C eq.3) E = A + D eq.4) C + E = A + B + D + F eq.5) A – B + C = B + E eq.6) B + C + F = D + E

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

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Hint #1


In eq.4, replace D + F with A + C (from eq.2): C + E = A + B + A + C Subtract C from both sides of the equation above: C + E – C = A + B + A + C – C which becomes eq.4a) E = 2×A + B


  

Hint #2


In eq.4a, replace E with A + D (from eq.3): A + D = 2×A + B Subtract A from both sides of the above equation: A + D – A = 2×A + B – A which becomes eq.4b) D = A + B


  

Hint #3


In eq.5, replace E with 2×A + B (from eq.4a): A – B + C = B + 2×A + B which becomes A – B + C = 2×A + 2×B In the above equation, add B to both sides, and subtract A from each side: A – B + C + B – A = 2×A + 2×B + B – A which becomes eq.5a) C = A + 3×B


  

Hint #4


In eq.2, substitute A + B for D (from eq.4b), and A + 3×B for C (from eq.5a): A + B + F = A + A + 3×B which becomes A + B + F = 2×A + 3×B Subtract A and B from both sides of the equation above: A + B + F – A – B = 2×A + 3×B – A – B which simplifies to eq.2a) F = A + 2×B


  

Hint #5


Substitute A + 3×B for C (from eq.5a), A + 2×B for F (from eq.2a), A + B for D (from eq.4b), and 2×A + B for E (from eq.4a) in eq.6: B + A + 3×B + A + 2×B = A + B + 2×A + B which becomes 2×A + 6×B = 3×A + 2×B Subtract 2×A and 2×B from both sides: 2×A + 6×B – 2×A – 2×B = 3×A + 2×B – 2×A – 2×B which simplifies to 4×B = A


  

Hint #6


Substitute 4×B for A in eq.5a: C = 4×B + 3×B which makes C = 7×B


  

Hint #7


Substitute 4×B for A in eq.4b: D = 4×B + B which makes D = 5×B


  

Hint #8


Substitute (4×B) for A in eq.4a: E = 2×(4×B) + B which is equivalent to E = 8×B + B which means E = 9×B


  

Hint #9


Substitute 4×B for A in eq.2a: F = 4×B + 2×B which makes F = 6×B


  

Solution

Substitute 4×B for A, 7×B for C, 5×B for D, 9×B for E, 6×B for F in eq.1: 4×B + B + 7×B + 5×B + 9×B + 6×B = 32 which simplifies to 32×B = 32 Divide both sides of the equation above by 32: 32×B ÷ 32 = 32 ÷ 32 which means B = 1 making A = 4×B = 4 × 1 = 4 C = 7×B = 7 × 1 = 7 D = 5×B = 5 × 1 = 5 E = 9×B = 9 × 1 = 9 F = 6×B = 6 × 1 = 6 and ABCDEF = 417596