# hee hee need help in Pri 4 Maths (again)

#### ed9119

##### Moderator
Staff member
should have joined the Maths Club and not Photo Club while in school :bsmilie:

K K A H
K J E D +
----------
H F K G
----------

What is K ? (0 to 9)

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#### allenleonhart

##### Deregistered
should have joined the Maths Club and not Photo Club while in school :bsmilie:

K K A H
K J E D +
----------
H F K G
----------

What is K ? (0 to 9)

wa i like. let the geek club handle. give me 20 mins i go shower first and cool down before thinking:thumbsup:
i'll just brute force it. btw there are 9 letters. meaning its most likely 1-9 or something

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#### marios_pittas

##### New Member
should have joined the Maths Club and not Photo Club while in school :bsmilie:

K K A H
K J E D +
----------
H F K G
----------

What is K ? (0 to 9)

I am blown!! I did PSLE 5 years ago and then 3 years ago... I am dreading my next one's !! :cry:

#### allenleonhart

##### Deregistered
ok. so far i figured out this far.

k ranges from 1-4 and cannot be bigger.

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#### allenleonhart

##### Deregistered
ok i got 1 combination out already

1132
1784+
2916

in this case, k=1

my logic

k+k cannot be greater than 10. or else u get an extra number after H

k+k will always be an even number.

so hence i deduced from here, k+k must be between 0-4.

in this case, h will range from 1-9. H cannot be 0. reason being, either K=0, or K+J must end up less than 10.

but since K exists, k will never equal to H, so the K=0 and H=0 case is impossible.
so leaves the next case: k+j less than 10. but if that happens, K is non zero, H will always give a value. reject 0 for H

now ur left with a few conditions

now i move on.
K cannot be 0. why?

if k=0, k not equal to H,
H must equal to 1.
yet for the condition to fufil, K+J and the remainder from A and E must be > 10. that means a+e must give a 10 at least.
so if u take 1+9, thats the only case to make H non zero, so that u have a value. if that happens, k=f, which is wrong.

so now i made it till k=1 to 4
h>0
now, u see another thing liao

K+K is non zero, meaning, sub smallest value in.
1+1.

H must be equal or larger than 1+1, meaning H must be >=2
now since i minimize my scope, i can try out and slowly test the cases 1 by 1.

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#### ed9119

##### Moderator
Staff member
can show working ? :bsmilie: :bsmilie: :bsmilie:

#### allenleonhart

##### Deregistered
can show working ? :bsmilie: :bsmilie: :bsmilie:
no working. i just brute force with knowing that k not equal to H, K ranges from 1-4 and H is larger than 2:think:

but if u really need...

place a value for k first.

let k=1

11??
1???
??1?

now can guess value for H. H must be larger or equal to 2, since k is non zero. so u have now H rangles from 2-9

so i let it be 2, or 3

11a2
1jed
2f1g

now u can guess, if all numbers are different
how to get 1 from A+e?
a+e can either give an 11, or give a 10, meaning 2+d will result in a value greater than 10.
i sub liao test for 2+d greater than 10, i get repeats. so its wrong.

so i move on to test a+e=11
so that means
3+8
4+7
5+6

i rest 5+6 i cannot, cause left 0,9,8,3,7. just wont work

so i test and test...

cause i know the value that K could be, it helps limit my scope. i know H range also. so i can guess liao.

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#### allenleonhart

##### Deregistered
btw ed, i think this is under the trial and error section. in psle, trial and error is given marks if u can do the table and show the tests u did.

i just minimize the scope with logic only. so i dun have to test so many

teach ur child logic base. let him understand how come u can limit the range. u dun have to test all combinations like this

oh yea. my logic is always

if add together, is it more than 10 or less? and i keep testing from there.

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#### ziploc

##### New Member
Wah why Pri 4 match so difficult? Are they teaching geniuses in Primary schools these days? Even a university student will have a hard time solving this. :sweat:

#### night86mare

##### Deregistered
should have joined the Maths Club and not Photo Club while in school :bsmilie:

K K A H
K J E D +
----------
H F K G
----------

What is K ? (0 to 9)

as allen has mentioned, should be 1-4, because K + K gives single digit number, it cannot be 5, since that would give H = 10, and i assume that each letter represents 0-9.

K cannot be 0, because K + K gives max H = 1 (spilling over from K + J = 1F, if this is the case, and if K is 0, then 1 + 0 (K) + J will give max 10, and that would mean that F = 0, which means that K and F are 0, unlikely).

after which you will have to brute-force it.

1 1 8 2 + 1 5 3 4 = 2 7 1 6

satisfies the requirement that each letter is a differnet number, but that is an assumed condition and is not something that we are told.

K = 1 in this case.

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#### brapodam

##### New Member
Yeah since when were Pri 4 students taught such advanced algebra?

#### snowspeeder

##### Senior Member
It's crazy, I've no idea what kind of math is that.

#### night86mare

##### Deregistered
anyways, this is with all the assumptions i have made, this question is so skimpy...

there has to be more conditions, or you can just free-ride it anyway you want, especially if different letters can represent same number.

#### allenleonhart

##### Deregistered

as allen has mentioned, should be 1-4, because K + K gives single digit number, it cannot be 5, since that would give H = 10, and i assume that each letter represents 0-9.

K cannot be 0, because K + K gives max H = 1 (spilling over from K + J = 1F, if this is the case, and if K is 0, then 1 + 0 (K) + J will give max 10, and that would mean that F = 0, which means that K and F are 0, unlikely).

after which you will have to brute-force it.

1 1 8 2 + 1 5 3 4 = 2 7 1 6

satisfies the requirement that each letter is a differnet number, but that is an assumed condition and is not something that we are told.

K = 1 in this case.
yep. u phrased my extremely messy logic into quite simple parts:thumbsup: thanks!

#### allenleonhart

##### Deregistered
Wah why Pri 4 match so difficult? Are they teaching geniuses in Primary schools these days? Even a university student will have a hard time solving this. :sweat:
in plimary 4 ur supposed to know how to brute force already:sweat:
i remember last time they used to ask for this kind of combinations one. usually they range it within 20-30 tries and u can get ans so its still quite ok.

#### ziploc

##### New Member
Putting it into equations:

G = (H + D) % 10, X = INT((H + D) / 10)
K = (A + E + X) % 10, Y = INT((A + E + X) / 10)
F = (K + J + Y) % 10, Z = INT((K + J + Y) / 10)
H = K + K + Z

As you can see above, I don't think you can't solve it via algebra as there are simply not enough info - nothing that defines D, A, E, J. It can only be done by brute force substitution.

#### brapodam

##### New Member
in plimary 4 ur supposed to know how to brute force already:sweat:
i remember last time they used to ask for this kind of combinations one. usually they range it within 20-30 tries and u can get ans so its still quite ok.
No they're putting too much stress on pri sch students. What kind of rubbish is this? We learn simple algebra like 3x + 4y = 15, 2x + y = 10, calculate x and y this kind of qn in sec 2, what kind of question is this?

Next thing you know they'll start teaching complex numbers and hypothesis testing in kindergarten...seriously

#### allenleonhart

##### Deregistered
Putting it into equations:

G = (H + D) % 10, X = INT((H + D) / 10)
K = (A + E + X) % 10, Y = INT((A + E + X) / 10)
F = (K + J + Y) % 10, Z = INT((K + J + Y) / 10)
H = K + K + Z

As you can see above, I don't think you can't solve it via algebra as there are simply not enough info - nothing that defines D, A, E, J. It can only be done by brute force substitution.

#### allenleonhart

##### Deregistered
No they're putting too much stress on pri sch students. What kind of rubbish is this? We learn simple algebra like 3x + 4y = 15, 2x + y = 10, calculate x and y this kind of qn in sec 2, what kind of question is this?

Next thing you know they'll start teaching complex numbers and hypothesis testing in kindergarten...seriously
LOL wont lar. brute force is just test numbers. pluck a few and try ur luck. not much to pluck in actually. K is the first one wanna identify, then guess H, (K+K) or (K+K+1)

which leaves u with 7 more numbers all DIFFERENT to guess with.

thats why i can do in 5 mins:sweat: