Cryptograms (Problem 4, Version 2)

Algebra Level 2

R G B R G B + R G B W B B B \large{\begin{array}{ccccccc} && R& G&B \\ && R& G&B\\ + & & R& G&B\\ \hline & W & B & B&B \end{array}}

Solve for W B B B \overline{WBBB} .

Note B , G , R , W B, G, R, W are different non-zero digits

Enter 1 -1 if there is definitely no solutions and you have proof.


The answer is -1.

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4 solutions

Chris Lewis
Jun 15, 2020

First note that the number 3 × B 3 \times B must end in the digit B B . We're told B B is not zero; so B = 5 B=5 . Writing out the rest as an equation, 300 R + 30 G + 15 = 1000 W + 555 300R+30G+15=1000W+555

Subtracting 15 15 from both sides and dividing by 10 10 : 30 R + 3 G = 100 W + 54 30R+3G=100W+54

We see that W W is a multiple of 3 3 . So the smallest the right-hand side can be is 354 354 . But the largest the left-hand side could be (obtained when R = 9 R=9 and G = 8 G=8 ) is 294 294 .

Therefore there are no solutions.

This is a very easy problem! W B B B = 3 R G B WBBB=3RGB , therefore 3 B + W m o d 3 = 0 3B+W\;mod\;3=0 . So W must be divisible by 3. But W < 3 W<3 , because W m a x ( = 987 3 ) = 2 961 W_{max}(=987*3)=\boxed{2}961 . Thus W = 0 W=0 , but the problem says that W W is a non-zero digit.

I can prove that there is no solution to this problem . Why then the answer 0 0 is incorrect? Following is the proof :

We are given that 3 ( 100 R + 10 G + B ) = 1000 W + 111 B 3(100R+10G+B)=1000W+111B

Hence W W must be divisible by 3 3 . Since it can't be zero, it's possible values are 3 , 6 , 9 3,6,9 . We will dwell with W = 3 W=3 here, the other alternatives can be proved in exactly the similar fashion.

For W = 3 , 100 R + 10 G = 1000 + 36 B W=3, 100R+10G=1000+36B .

So B B must be 5 5 . Then

10 R + G = 118 10R+G=118 , which is impossible, since the maximum possible value of 10 R + G 10R+G is 99 99 .

I will edit it.

Mahdi Raza
Jun 15, 2020
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total = 0

for w in range(1, 10):
    for r in range(1, 10):
        for g in range(1, 10):
            for b in range(1, 10):
                if (3 * (100 * r + 10 * g + b) == 1000 * w + 111 * b):
                    total = total + 1
                    print(w, r, g, b)

print(total, "solutions")

1
0 solutions

Thank you! @Mahdi Raza

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You're Welcome!

Mahdi Raza - 12 months ago

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