Thank u so much Stacey and Yeo See Yeong for your help.

I had one question Stacey Tan. How $500 = 2u

Because from the model drawing, we can see that there are 3 units not shaded. And we are told that she has 1/3 of her salary left. So we can conclude that 3 units make up the 1/3 of her salary. Since 3 units make up 1/3 of her salary, it means that 9 units will make up her full salary. All the units are of the same size. Since there are only 7 of the units, it means that the 2 missing unit is made up by the $500. So we conclude that the 2 units = $500.

[explain with model drawing] The last model drawing shows the salary divided into 3 portions (boxed up in red). We can see that the first box has only one unit and $500. Since each box needs 3 units, so the 2 units is the $500.

Sum of the four 3 digit number is 250 x 4 = 1000. Sum of the other 2 numbers = 1000 - 190 - 230 = 810-230=580. Assuming by numbers we define it as 1 to infinity, so the largest difference is when 1 number is 100(3 digits) and other number is 480. In this case the largest difference is 480-100 = 380. Actually they should define numbers as positive integers.

Sorry AisinGioro YongZhen... the sum of the last two numbers is 580 (correct), but the smaller number can only be 100. So the larger number is 480. Difference is thus 380.

Wow, so which emperor was correct?

the smaller number cant be 1 as the Q specifically wrote "average of four 3-digit" numbers.

It was stated that the numbers are all 3 digits. Total of the 4 numbers= 250x4=1000 Total of the 2 known numbers = 190+230=420 Total of the 2 unknown numbers = 1000-420=580 Smallest 3 digit number is 100 So the other number is 580-100=480 Difference between the largest and smallest = 480-100=380 *thanks Shu Hao, corrected the computation error.

1000-420＝580

aw forgot about 3 digits , smallest should be 100 and biggest 480 sorry about it.

... what...?

sry abt it, i am thinking if the smallest digit can be -999? since it is 3 digits

neg numbers are not in PSLE syllabus

ok ok thx.

I don't understand why 580-100 & 480-100?

so in general we only consider 0 ,1,2,3,... No wonder kids look blur when -ve numbers are involved in word problems

sorry it should be 480-100, because 580 is the sum of the remaining 2 numbers, so 1 number shld be 100 (the smallest) then 480 is obtained by taking 580 - 100

This will yield us the greatest difference as we have selected 100 which is the smallest 3 digit number possible.

Why 580-100 Because total of the 2 numbers is 580. Smallest possible number is 100. Therefore the other number has to be 580-100=480 [that will mean that one number is 100 and the other number is 480]

Why 480-100 Because the question ask for the difference between the big number (which is 480) and the small number (which is 100). So we minus to find the difference.

Noted with thanks

Oh my goodness...

Stacey Tan, how did u do it??

Thank u v much. U r a genius! ☆☆

Sudoku method but need to take care of the constraints given ( greater and smaller sign). Take me a while but I enjoy doing such questions. 😜

i play sudoku everyday on my journey to work. but such constraints kill me. you should join 最强大脑！

Thanks so much

I know from which company. By right no homework should be given for enrichment programme. Not sure u that trainer has given ur kid homework. :)

Not sure y**

wow, got sudoko, that day I was doing Magic squares and a bit of number theory and combinatorics to help someone's kid, pretty scary syllabus at p6

I ask my neighbour. She very good at sudoko puzzles

Thanks Junnevaeh Lim

Sudoko is a good number game logical thinking. Brain stimulator. I started my girl with this type of simple Sudoko when she's in P2. Now in P4 she can do the 9x9 game.

Eg: start with no 3. If you see rowC there's a 3 in box CD456. So no 3 in box CD123 cannot be in rowC. Only options left are cells D1 or D3. However if you look down in column 1, you hv a 3 in box EF123. Thus this eliminate the D1 option leaving you only with D3. So for box AB123, with no.3 already in column 1 and 3, the only option you have left is in cell B2. Then you can move on to box AB456 and EF 456. Using the same logic, work on each number, logic and elimination method to place the numbers. As mentioned, you can only have 123456 in each row, each column or each box. The numbers cannot be repeated.