Triangular cryptogram

Logic Level 1

A B C D E F \begin{array}{ccccc} & & & A & B & C\\ - & & & & D & E \\ \hline & & & & & F \end{array}

In the cryptogram above, the six letters are different digits and neither A A nor D D is zero.

Which of the following can be a value of F ? F?

1 2 3 4

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14 solutions

Venkatachalam J
Jun 18, 2018

The greatest distinct 2 digit number subtracted from the smallest distinct 3 digit number is 102 - 98 = 4, which is the smallest value of F. Therefore, F equal to 1, 2, and 3 are not possible. Hence the solution is 4.

Not helpful

Lalit Yadav - 2 years, 11 months ago

Very helpful

A Former Brilliant Member - 2 years, 11 months ago

yah not helpful

Video Perfection - 2 years, 11 months ago

Thank you!

Alina Shcherbakova - 2 years, 11 months ago
Stephen Mellor
Jun 15, 2018

Since the subtraction results in a one digit number it is evident that it is 10 C 9 E = F \overline{10C} - \overline{9E} = F . As these above digits have already been used, to get the smallest value of F, we let C = 2 C = 2 and E = 8 E = 8 . This means that the smallest possible value of F is 4.

Similar thinking! (+1)

Noel Lo - 2 years, 11 months ago

Easy to crack

Aarush Priyankaj - 2 years, 11 months ago

Nice solution by thinking about the smallest possible F!

Gaurav Pundir - 2 years, 11 months ago

Did the same. 4 is obviously the smallest possible value of F. I clicked the 4th choice but it's marked incorrect. Why's this @Pi Han Goh ? :)

Geneveve Tudence - 2 years, 11 months ago

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Hi Geneveve, the system shows that you have submitted an answer of 3, not 4.

Brilliant Mathematics Staff - 2 years, 11 months ago

Did the staff just expose you? What?

Long Plays - 2 years, 11 months ago

Well 236+47 =283

Anmol Arichwal - 2 years, 11 months ago

sorry for my mistake it is plus sorry

Anmol Arichwal - 2 years, 11 months ago

109 - 78 =1 208 - 56 =2 307 - 34 =3

Non digit repeated, A&D is not zero. The value of F can be all of the given answer. What with the smallest value of F is 4. Can you enlighten me please?

يوسف محمد صالح - 2 years, 11 months ago

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F is a single digit number, not just the units digit of the result

Stephen Mellor - 2 years, 11 months ago

Jus try to make the smallest number with unique A,B,C,D,E. This is clearly 102 98 = 4 102-98=4 . Since no smaller number can be made, this eliminates 1,2,3. Therefore the answer should be 4 \boxed{4}

Although that's kinda confusing, it's sensible.

David Warrak - 2 years, 11 months ago

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not sensible, nobody stated smallest possible 3 variable number... all solutions are correct. smh

victor vosen - 2 years, 11 months ago

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The other numbers, 1 2 and 3, are SMALLER than the answer of 4, so since you concede that 4 is clearly the smallest possible, the other answers are INCORRECT, and not CORRECT at all. I thought you were joking.

Adrian Self - 2 years, 11 months ago

since the law of permutability dictates all variables could be anything... All Solutions Are Correct For Every Real Number!

victor vosen - 2 years, 11 months ago

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Wrong... The answer cannot be 1,2 or 3. Read the solution carefully.

Chandrashekar Giridharan - 2 years, 11 months ago

It was a joke, presumably

Adrian Self - 2 years, 11 months ago

When solving, the simplest solution makes an excellent starting point. Because of this, I started with the smallest possible number for ABC, then narrowed down the possibility for DE. It's more of a logic game than a mathematical puzzle; once you accept that each letter must have a different value, and neither A or D are zero, the answer emerges.

Kourtnie McKenzie - 2 years, 11 months ago

But can't you have 140-39 for instance ?

br o - 2 years, 11 months ago

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No; we are looking for a single-digit, decimal value of F

Adrian Self - 2 years, 11 months ago

Cant we do like 100-99 equal to 1? Or 100-98 equal to 2?

Syed Shah - 2 years, 11 months ago

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You see, all the digits are distinct or (say) different.You said - 100 - 99 = 1... And 100 - 98 = 2... In the first case...'00' and '99' repeat.. and second one '00' of 100 repeat.

Prem Chebrolu - 2 years, 11 months ago
Siva Budaraju
Jun 7, 2018

102-98=4 is one.

Griffin Trayner
Jun 18, 2018

If F is the solution, then A must be 1 and D must be 9. Also, B must be 0.

Now we have 10C - 9E = F

100 - 90 + (C - E) = F

10 + C - E = F

Since digits 1,0, and 9 have been used, and C<E if F is positive, then we can make the following inequalities:

1<C<7

2<E<8

We can then try values, which yield values of F from 4 to 9. 4 is the only valid choice in the problem, so 4 is a possible value.

Adrian Mišak
Jun 24, 2018

It holds that A=1, because if A is greater, then it wouldn't be possible to get a single digit result by subtracting two-digit number from A. So, then we get: 100+10B+C=F+10D+E. The right hand side has an upper bound of 105 (D=9, F=9, E=8 for example), so B must be 0 (if B is not zero, then the left side is at least 120, since digits need to be different). We have a lower bound of 102 for the left side. It remains to look at what is possible and what not.

Toby Harris
Jun 23, 2018

The largest number (ABC) has to be a small 100’s number and the smallest number has to be a large 90’s number. We can’t have 104 and 95, say, because the difference is greater than any of the options. Also, each digit is distinct, as it says in the question, so you couldn’t have 102 and 99 (difference of 3), so 3 can’t be right.

A difference of 2 is not possible as the two numbers would violate the distinct digit rule (102 and 100 say).

A difference of 1 is not possible either for the same reasons as a difference of 2.

This leaves the only possible answer to be 4 (102 and 98).

Lynn Phillips
Jun 22, 2018

Each digit is a different number eliminating numbers like 100-99. Smallest 3 digit number you can create with that is 102. You must then subtract a 2 digit number to get a 1 digit number or work the other way around eliminating 1 and 2 because you will get 101 or 100 which repeat numbers. 3 is out when you realize 102-3=99, repeating numbers. Only option left is 4.

Edwin Gray
Jun 18, 2018

We ned ABC to be the smallest 3 digit number, since A .ne. 0. 103 cannot work since subtracting the largest 2 digit number with different digits(98), gives an answer of 5. 101 contains 2 of the same digits, so we settle on ABC = 102, leaving DE to be 98, with a difference of F = 4. Ed Gray

Chew-Seong Cheong
Jun 18, 2018

Since A B C D E = F \overline{ABC}-\overline{DE} = F D E + F = A B C \implies \overline{DE}+F = \overline{ABC} . It is obvious that A = 1 A=1 , since the largest D E + F = 98 + 7 = 105 \overline{DE}+F = 98+7 = 105 and that D = 9 D=9 and E + F 10 E+F \ge 10 . Since A = 1 A=1 , F 1 F \ne 1 . If F = 2 F=2 , D E + F = 98 + 2 = 100 \overline{DE}+F = 98+2 = 100 , then B = C B=C not acceptable. F = 3 F=3 98 + 3 = 101 \implies 98+3 = 101 , A = C A=C not acceptable. F = 4 F=4 , 98 + 4 = 102 \implies 98+4 = 102 , all the digits are distinct. Therefore, F = 4 F=\boxed{4} is acceptable.

One solution:

Note that the minuend is a three digit integer, the subtrahend is a two digit integer and the difference is a one digit integer. So we start with the minuend, it must be the lowest three digit number with distinct digits and that is 102. Then the subtrahend must be the highest two digit number with distinct digits and that is 98. Subtracting 98 from 102 gives a difference of 4.

Phạm Hoàng
Jun 21, 2018

First we see all answer in above are small so A B C \overline{ABC} have to be 3 digit smallest distinct number & D E \overline{DE} have to be 2 digit distinct number.Next the smallest 3 digit distinct number of A B C = 102 \overline{ABC}=102 .After that the biggest 2 digit distinct number of D E = 98 \overline{DE}=98 .So,the F F is 4 \color{#3D99F6}\boxed{\large{4}}

Gil Costa
Jun 21, 2018

102 - 98

is the extreme case...

Jochen Morent
Jun 17, 2018

Since the 100 digit of the result is 0, A can only be 1.

Therefore B needs to be smaller then D. The difference of B and D as well as a potential carryover need to be 10, so that there is a carryover to cancel the 1 of A and have a 0 for the 10th digit of the result. Since the carryover can only be 0 or 1 the formula is B - D = -10 or B - D - 1 = -10 Since we are working with digits the only possible combination is: B = 0 and D = 9 with a carryover of 1.

Sofar it's 10C - 9E = F

Since we need a carryover for the 10th digit C needs to be bigger then E.

If C = 2 and ... E = 3, then F = 9 which is no destict digit E = 4 or 5, then F = 8 or 7 E = 6, then F = 6 which is no destict digit E = 7 or 8, then F = 5 or 4

There we already have one of the values in the selection. Due to the wording of the question this is enough and we can use 4 as the answer.

I want to complete the possible combinations for C, E and F.

If C and E are only one apart then F is 9 and therefore not destict.

If C is even (2,4,6) there is one combination of E and F where they are not distinct. For all the odd numbers for C as well as the other combinations for even values of C there are distinct combinations for E and F, with the values of 8 down to C + 2.

Since all those combinations will produce values for F between 8 and 4 there won't be any other values from the options.

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