Puzzle for May 30, 2022  ( )

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

eq.1) A + B + C + D + E + F = 25 eq.2) D = C + F eq.3) B = C + D eq.4) A = B + C eq.5) E + F = B + D eq.6) C + E = B + D + F

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

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Hint #1


In eq.6, replace B + D with E + F (from eq.5): C + E = E + F + F which becomes C + E = E + 2×F Subtract E from each side of the equation above: C + E – E = E + 2×F – E which makes C = 2×F


  

Hint #2


In eq.2, replace C with 2×F: D = 2×F + F which makes D = 3×F


  

Hint #3


In eq.3, substitute 2×F for C, and 3×F for D: B = 2×F + 3×F which makes B = 5×F


  

Hint #4


Substitute 5×F for B, and 2×F for C in eq.4: A = 5×F + 2×F which makes A = 7×F


  

Hint #5


Substitute 5×F for B, and 3×F for D in eq.5: E + F = 5×F + 3×F which becomes E + F = 8×F Subtract F from each side of the equation above: E + F – F = 8×F – F which makes E = 7×F


  

Solution

Substitute 7×F for A and E, 5×F for B, 2×F for C, and 3×F for D in eq.1: 7×F + 5×F + 2×F + 3×F + 7×F + F = 25 which simplifies to 25×F = 25 Divide both sides of the above equation by 25: 25×F ÷ 25 = 25 ÷ 25 which means F = 1 making A = 7×F = 7 × 1 = 7 B = 5×F = 5 × 1 = 5 C = 2×F = 2 × 1 = 2 D = 3×F = 3 × 1 = 3 E = 7×F = 7 × 1 = 7 and ABCDEF = 752371