Scrambled Additions

Logic Level 2

X Y Z + X Z Y Y Z X \begin{array}{ccccc} & & & X & Y&Z\\ + & & & X & Z & Y \\ \hline & & & Y & Z & X\\ \end{array}

Let X , Y X,Y and Z Z be three distinct single digits satisfying the cryptogram above with X 0 X\ne 0 . Find the value of the three digit integer, X Y Z \overline{XYZ} .


The answer is 495.

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9 solutions

In the ten's place, we have Y + Z = Z Y+Z=Z , this means that Y = 0 Y=0 or Y = 9 Y=9 . (9 being the case of having a carry forward from the unit's place).

However, because the result is three digit number, Y = 9 Y=9 .

From this, we can say that X = Z 1 X=Z-1 (seeing the units place)

and also X = 4 X=4 (observing the hundred's place) and finally Z = 5 Z=5 .

Which gives X Y Z = 495 \overline{XYZ}=\boxed{495} .

James Church
Dec 22, 2015

My solution is not going to be very well formated but here is my solution. XYZ + XZY = YZX XYZ = 100X + 10Y + Z XZY = 100X + 10Z + Y YZX = 100Y + 10Z + X Simplifying produces 200X + 11Y + 11Z = 100Y + 10Z + X Bring all the terms to one side 199X + Z - 89Y I don't know if there is a way to directly figure it out from here but after placing numbers in the equation 199x4=796 X=4 Z=5 89x9=801 Y=9 Placing them back in the problem gives you: 459+495=954 the correct answer!

Armain Labeeb
Jun 22, 2016

I am never good at cracking cryptograms so I did it this way:

We have,

X Y Z = 100 X + 10 Y + Z ( 1 ) X Z Y = 100 X + 10 Z + Y ( 2 ) Y Z X = 100 Y + 10 Z + X ( 3 ) X Y Z + X Z Y = Y Z X ( 4 ) \overline { XYZ } =100X+10Y+Z\quad \rightarrow (1)\\ \overline { XZY } =100X+10Z+Y\quad \rightarrow (2)\\ \overline { YZX } =100Y+10Z+X\quad \rightarrow (3)\\ \overline { XYZ } +\overline { XZY } =\overline { YZX } \quad \quad \rightarrow (4)

Substituting equations ( 1 ) (1) , ( 2 ) (2) and ( 3 ) (3) into equation ( 4 ) (4) ,

100 X + 10 Y + Z + 100 X + 10 Z + Y = 100 Y + 10 Z + X 199 X 89 Y + Z = 0 199 X = 89 Y Z ( 5 ) \quad \quad 100X+10Y+Z+100X+10Z+Y=100Y+10Z+X\\ \rightarrow 199X-89Y+Z\quad \quad \quad \quad \quad \quad \quad \quad \quad =0\\ \rightarrow 199X\quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad =89Y-Z \quad \quad \rightarrow (5)

X X , Y Y and Z Z must be single digit integers.

As they are all distinct positive single digit integers, 89 Y Z 89Y-Z would be slightly bigger than 199 X 199X .

By logic and a bit of arithmetic, the value of Y Y would be more than 199 + 0 89 = 200 89 2.23 \frac { 199+0 }{ 89 } =\frac { 200 }{ 89 } \approx 2.23 times but less than 199 + 10 89 = 209 89 2.35 \frac { 199+10 }{ 89 } =\frac { 209 }{ 89 } \approx 2.35 times the value of X X .

In other words, 199 89 Y X < 209 89 \frac { 199 }{ 89 } \le \frac { Y }{ X } <\frac { 209 }{ 89 } .

The only pair of single digit integers where 199 89 Y X < 209 89 \frac { 199 }{ 89 } \le \frac { Y }{ X } <\frac { 209 }{ 89 } is when ( X , Y ) (X,Y) is equivalent to 4 , 9 4,9 . Thus we can conclude X = 4 X=4 and Y = 9 Y=9 .

Substituting X = 4 X=4 and Y = 9 Y=9 into equation ( 5 ) (5) ,

199 X = 89 Y Z 199 ( 4 ) = 89 ( 9 ) Z Z = 501 496 = 5 \quad \quad 199X\quad \quad \quad \quad =89Y-Z\\ \rightarrow 199(4)\quad \quad \quad \quad =89(9)-Z\\ \rightarrow Z=501-496\quad =5

Hence,

X Y Z = 495 \overline { XYZ } =\boxed { 495 }

Consider that X not equal to Z Z+Y = X+10 --------------------- (1) Z+Y+1 = Z+10 --------------------- (2) X+X+1 = Y

2X+1 = Y --------------------- (3) Z+2X+1 = X+10

X+Z = 9 ---------------------- (4)

Substituting (1)-(2), X-Z = -1 ---------------------- (5) 2X = 8 X = 4 Substituting X=4 in (3) Y = 9 Substituing X=4 in (4) Z = 9-4 = 5

495+459=954

I like this solution and can understand easily

Shantha Shanker - 1 year, 9 months ago
Joshua Burks
Jan 21, 2018
  • (A) z+y=x+CO(A) x cannot be 0; x, y, and z cannot be > 9; x cannot = y cannot = z
  • (B) y+z+CO(A)=z+CO(B) y and z cannot be > 9, y cannot = z
  • (C) x+x+CO(B)=y x cannot be 0; x and y cannot be > 9, x cannot = y
  • Any carryovers (CO) are equal to 100, 10, or 0 depending on positions. If CO(B) exists it would be 10 x CO(A) if it exists or they coexist.
  • I left out the math for the conversions.
  • From (C) x=(y-(CO(B))/2
  • From (B) y+z+CO(A)=z+CO(B)
  • y=CO(B) - CO(A)
  • CO(A) can be 1 or 0 and CO(B) can be 10 or 0 for (B)
  • therefore y can equal 10,9,0,and -1
  • 10 can be removed because y cannot be > 9
  • 0 can be removed because x=(0-0)/2 and x cannot equal 0
  • -1 can be removed because x=(-1-0)/2=-1/2; x has to be a whole number
  • So, due to positions, CO(A) = 10 for (A), CO(B) = 10 and CO(A) = 1 for (B), and CO(B) = 1 for (C) and
  • y=9;
  • x=(9-1)/2=4;
  • z=4-9+10=5;
  • So, 495.
Peter Labeb
May 21, 2016
  • Z+Y=X+10 eq1
  • Y+Z+1=Z+10 eq2 then Y= (9) eq3
  • 2X+1=Y eq4
  • from 3,4 2X+1=9 then x=4 eq5
  • from 3,5 Z+9=4+10
  • Z=5
  • XYZ = 495
Dario Alise
Jan 3, 2016

From the (1) column we know that Z+Y = X, from the (2) column we know that Z+Y = Z. This is not possibile for hypothesis, unless we admit that Z+Y>10 so we have carry-over and X={Z-1, Y-1} o X=min{Z,Y}-1. Since the same sum appears in the (2) column, we have the carry-over also for this column, and, because the result under column (3) have one digit, it means that X≤4. So we have that 10<Z+Y≤14. We have some two possible set {Z, Y, X} = {5, 9, 4}, {9, 5, 4}. All the other set must be excluded because don't respect the rules. In particular we must remove also the second set, because if we have two number, x and y, the sum x+y≤17, so we can't have 9. This means that the correct choice is {Z, Y, X} = {5, 9, 4}

Gareth Adamson
Dec 28, 2015

Well, we know that X must be < 5, since the answer is a 3-digit number.

We also know that Y has to equal either 0 or 9, since Y + Z = Z.

However, since X + X = Y, and X =/= 0, Y cannot be 0 (and therefore must be 9).

Now that we know Y is 9, X + X must equal 9. This is only possible with a carry from the tens place (4 + 4 (+1) = 9). Therefore X must equal 4.

For Z, we know that Z + 9 = 4. Z cannot be -5, and therefore must be 5 (5 + 9 = 4 with a carry of 1). This also works with the tens place.

Therefore XYZ = 495.

Andrea la Monaca
Dec 28, 2015

X must be smaller than 5. At each step assume x=i with i=1,..,4. For each x fixed, y could be 2x or 2x+1. For each value of y fixed, z is obtained looking at the units' column. Iterating this procedure at the step i=4 we have that y could be 8 or 9. For y=9 results z=5, finally 495

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