MATHS!

Warning: VERY Mathematical Content!
This may cause extreme discomfort and confusion to some people.
The author blogger shall not be responsible for any mishaps or whatsoever that might occur while reading the entry. Viewer Reader discretion is advised.

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The first 3 questions are...

First Question:
On the bus there are 7 girls, each girl have 7 bags, each bag contains 7...........
^^ I stated this question before. Flip the archives if you want the full question and answer.

Second Question:
Given the 4 numbers, 3, 4, 5, and 6 only, what is the largest number you can form such that it cannot be divided by 9?

Answer: 654.
Don't believe it? Try arranging the 4 numbers, in any order... All arrangements will be divisible by 9 as long as all 4 numbers are used.

Third Question:
What is the last digit of the sum of all the numbers from 1 to 99?

Im amazed by the number of ways to solve this question. And do you know that this is a PSLE question that came out in year 2000??
The answer is 0.
Simplest way I can come out with...
1 + 9 = 10, 2 + 8 = 10, 3 + 7 = 10, 4 + 6 = 10
In this case, can I assume that all numbers that start from 1 to 4 and 6 to 9 will add up to become a number which last digit is 0?
Numbers that do not end with 1 to 4 or 6 to 9 = Multiples of 5...
5 15 25 35 45 55 65 75 85 95 & 10 20 30 40 50 60 70 80 90
Even number of multiples of 5 dat ends with 5 = Sum will end with 0
Odd number of multiples of 5 dat ends with 5 = Sum will end with 5
Do I still have to say more for those that ends with "0"?
Ok... Now you got it?
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Lesson learnt...
Think outside the box!!
But... How can we think outside the box when we are working inside a cube???

Finally the program my sis had been downloading SINCE AFTERNOON has been completed!
Now I can go murder hibernate her computer.
Sleeping after I post this. Nights...

Current mood: =)
Out