The Alien Calculator Quiz | Brain Teasers

Quiz Answer Key and Fun Facts

1. Operator: Division

(Note: For better legibility, I am presenting the info row by row as it is deduced)

Row 1 on the right tells us several things: Firstly, the aliens use reverse Polish notation, so you put the first operator, then a separator, then the second operator and finally the operation.

With both input digits and the output being the same, we know the digit has to be either 0 or 1. We don't know which of them, however.

Key 15 = input separator.

2. Operator: Addition

Row 2 gives us the other digit that must either be a 0 or a 1. We still do not know which of them is which. Let's go on.

3. Operator: Multiplication

Starting row 3, we know the digits involved to be 1 and 0. The only way to use these two and an operation to give the displayed result is to subtract 1 from 1, giving 0. Therefore:

Key 4 = subtract, key 5 = digit 0 and key 9 = digit 1.

4. Operator: Subtraction

Row 4 seems rather unhelpful at first glance, but it is anything but. First, the result has a leftmost 0, so we can conclude the aliens display their numbers right to left. Since we also know the other result digit is not 1, we know the operation here to be multiplication (addition can't reach that high a number). This leaves addition and division for operators in the first two rows. Since row 1 is not an error, it must be 0+0=0 and row 2 is 1/1=1.

We can't yet fully conclude which digits are involved in the multiplication. Let's move on

Key 1 = division, key 2 = addition, key 3 = multiplication.

5. Digit: 0

With all we know about the first four rows, we know the input of row 5 to be 1+1=..., so the result symbol is a 2.

This knowledge will come in handy for the next row.

Key 6 = digit 2.

6. Digit: 2

Row 6 shows a division, and both the divisor and the quotient are 2. So the dividend is a 4? No - because we have something else, namely a 1 offset to the right. Since this must mean something (we had no such thing on row 2), it has to be a remainder, making the dividend a 5.

Key 13 = digit 5.

7. Digit: 8

Row 7: 2 multiplied by something gives 10. But wait, didn't we already have the 5 and this isn't it? But wait, the calculator has 12 digit keys, not 10. So it's safe to conclude our aliens use a duodecimal system and the unknown second factor is actually a 6.

(The fiendish author of this quiz has stealthily omitted two of the keys from the answer to make this conclusion not too obvious...)

Key 8 = digit 6.

8. Digit: 6

Row 8: 5 and something added together give 12 (14 decimally). So we now know the 9. Armed with that knowledge, we can look back at row 4 and solve the multiplication: 9 times something is 60 (decimal 72), yielding the 8.

Key 14 = digit 9, key 7 = digit 8.

9. Digit: 1

Almost there. Before analysing row 9, we now know everything but the digits for 3, 4, 7, T (decimal 10) and E (decimal 11). We have a subtraction here, and the subtrahend is 8. So E - 8 = 3? Nope, because that result symbol is not present on any key. Looking carefully, it is an upside down mirrored version of the minuend. Could this be a negative number? Certainly, 4 - 8 = (-4) would work.

Let's look one row further before locking this in.

10. Digit: 7

We have another division at hand in row 10. x divided by y gives y, rest 2. Since x is a single digit, it must be less than 12. The only way to resolve this with the remaining unknowns is x = E (decimal 11) and y = 3. Looks like our assumption regarding row 9 was thus correct.

Key 12 = digit 3, key 11 = digit 4.

11. Digit: 4

Row 11. We're only missing the 7 and the T (decimal 10) and the result of this subtraction is an upside-down 3. This fills in the last two slots (even if you overlooked the somewhat hard to see mirror here at first, there is no T in the answer options, so hopefully this didn't cause you much trouble.

Key 10 = 7.

12. Digit: 3

We've figured everything out required for answering the quiz, so let's just analyze the remaining rows. In row 12, we have 195 (decimal 257) *times 8 = 1234 (decimal 2056). We thus learn that the aliens do at least one thing like we do: They push the most significant digit's key first.

(We also see that obviously the aliens have invaded one FunTrivia team :) - this was completely unintentional in quiz creation)

13. Digit: 5

Row 13 and 14 just confirm what we have learned: 88 (decimal 104) + EE (decimal 143) is 187 (decimal 247) and 12 (decimal 14) minus 21 (decimal 25) is negative E (-11).

14. Digit: 9

One further division with a remainder is shown in row 15: 40 (decimal 48) divided by 5 is 9, remainder 3. Everything matches up!

15. Input Separator

And finally, the last row contains the truth, which is, of course 42 (decimal 50), arrived at by multiplying 5 and T (decimal 10).

Even our aliens, however, can't make the "Hitchhiker's Guide" equation of 6 multiplied by 9 being 42 true however - you'd need a base of 13, not 12, to make that one work.

Source: Author WesleyCrusher

This quiz was reviewed by FunTrivia editor Fifiona81 before going online.
Any errors found in FunTrivia content are routinely corrected through our feedback system.

The Alien Calculator Trivia Quiz

In 2047, WSEA (World Space Exploration Agency) astronauts found this alien pocket calculator on Mars. It was still in working order, so they could enter some calculations. Can you figure out which key / symbol stands for which digit or operation?

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