Puzzle for August 10, 2020  ( )

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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) A + E = B eq.4) E – A = B – E eq.5) B – F = A + F eq.6) C – B – E = A + B – C

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 B with A + E (from eq.3): E – A = A + E – E which becomes E – A = A Add A to both sides of the equation above: E – A + A = A + A which makes E = 2×A


  

Hint #2


In eq.3, replace E with 2×A: A + 2×A = B which makes 3×A = B


  

Hint #3


In eq.5, substitute 3×A for B: 3×A – F = A + F In the equation above, add F to both sides, and subtract A from both sides: 3×A – F + F – A = A + F + F – A which makes 2×A = 2×F Divide both sides by 2: 2×A ÷ 2 = 2×F ÷ 2 which makes A = F


  

Hint #4


Substitute 3×A for B, and 2×A for E in eq.6: C – 3×A – 2×A = A + 3×A – C which becomes C – 5×A = 4×A – C Add 5×A and C to both sides of the above equation: C – 5×A + 5×A + C = 4×A – C + 5×A + C which becomes 2×C = 9×A Divide both sides by 2: 2×C ÷ 2 = 9×A ÷ 2 which makes C = 4½×A


  

Hint #5


Substitute A for F, and 4½×A for C in eq.2: D + A = A + 4½×A which becomes D + A = 5½×A Subtract A from each side of the equation above: D + A – A = 5½×A – A which makes D = 4½×A


  

Solution

Substitute 3×A for B, and 4½×A for C and D, 2×A for E, and A for F in eq.1: A + 3×A + 4½×A + 4½×A + 2×A + A = 32 which simplifies to 16×A = 32 Divide both sides of the equation above by 16: 16×A ÷ 16 = 32 ÷ 16 which means A = 2 making B = 3×A = 3 × 2 = 6 C = D = 4½×A = 4½ × 2 = 9 E = 2×A = 2 × 2 = 4 F = A = 2 and ABCDEF = 269942