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**mathsyperson****Moderator**- Registered: 2005-06-22
- Posts: 4,900

It's only a problem if you have a number or algebraic expression at the end of your sentence though. It's fine to be emotional as long as you use strategic sentence structure.

"And now by reducing the fraction, we can see that the equation is solved!"

You could also possibly get around it by saying "And now we see that the answer is two!" or similar, depending on how strict the teacher is. I've never seen factorials applied to numbers as words.

Although technically, if the answer was 2 then saying 2! wouldn't even be wrong.

Why did the vector cross the road?

It wanted to be normal.

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**ganesh****Moderator**- Registered: 2005-06-28
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18. If 1000 kilobytes is a megabyte,

1000 megabytes a gigabyte, what is 1000 gigabytes?

19. What would be the last digit of 6^100?

20. Is 1001 a prime number?

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**Devantè****Real Member**- Registered: 2006-07-14
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18. 1 Terabyte

19. I'll come back to later

20. No

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**luca-deltodesco****Member**- Registered: 2006-05-05
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19. 6

The Beginning Of All Things To End.

The End Of All Things To Come.

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**Devantè****Real Member**- Registered: 2006-07-14
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Oops, didn't realise 6^n (n not being 0 or 1) would always end in a 6.

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**ganesh****Moderator**- Registered: 2005-06-28
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Excellent, devante` and luca-deltodesco!!!

To devante` : Any power of a number ending in 0,1,5,6 always end in 0,1,5,6 respectively.

21. Is 133 a prime number?

22. How many squares are there from 1 to 1000, inculding 1?

23. And how many cubes?

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**ganesh****Moderator**- Registered: 2005-06-28
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24. Whats special about the number 0.4771................?

25. How many cubes, including 1, are there from 1 to 1000?

Character is who you are when no one is looking.

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**Devantè****Real Member**- Registered: 2006-07-14
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21. No

22. Hmm...31?

23. 10

24. The mark for 3 is located about 0.4771 units from the mark for 1 (to do with Slide Rules)

25. Haven't you already asked that question? Anyway, 10.

Oh, and thanks Ganesh for that.

I wasn't taught that rule.

*Last edited by Devanté (2006-09-29 03:51:41)*

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**ganesh****Moderator**- Registered: 2005-06-28
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26. What is 6 x 6 x 6?

27. Is 343 a prime number?

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**mathsyperson****Moderator**- Registered: 2005-06-22
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26. 216

27. No. If you take the last digit of 343 and multiply it by 2, then take that away from the rest of 343, you get 34 - (2*3) = 28. 28 is divisible by 7, which means that 343 also is.

...OK, I just wanted to show off that cool method that I know of finding multiples of 7 that probably takes longer than just dividing the number by 7 anyway. But I recognised that 343 was 7³, so I still did it in under 10 seconds.

Why did the vector cross the road?

It wanted to be normal.

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**ganesh****Moderator**- Registered: 2005-06-28
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Excellent, mathsyperson!

Knowing 343 is 7^3 is remarkable!!!

28. What is 6!?

29. Aprroximately how many kilometers is a light year?

30. What is sin45+cos45 (degrees)?

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**espeon****Real Member**- Registered: 2006-02-05
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u know 28 what does the !?mean?

Presenting the Prinny dance.

Take this dood! Huh doood!!! HUH DOOOOD!?!? DOOD HUH!!!!!! DOOOOOOOOOOOOOOOOOOOOOOOOOD!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

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**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 15,142

! means factorial.

1! is 1.

2! is 2x1=2.

3!=3x2x1=6.

4!=4x3x2x1=24

5!=5x4x3x2x1=120.

Factorials are very important in combinatorics. Like finding permuations and combinations. espeon, you would soon be taught in school about permutations and combinations in probability. You can refer our formuls section for getting the formulas.

Character is who you are when no one is looking.

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**espeon****Real Member**- Registered: 2006-02-05
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so ! means everything upto it so 6! is

6x5x4x3x2x1=720?

Presenting the Prinny dance.

Take this dood! Huh doood!!! HUH DOOOOD!?!? DOOD HUH!!!!!! DOOOOOOOOOOOOOOOOOOOOOOOOOD!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

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**ganesh****Moderator**- Registered: 2005-06-28
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Very well done, espeon! You are correct!

7! is 7x6x5x4x3x2x1=5040

9! is 9x8x7x6x5x4x3x2x1 = 362880

10! is 10x9x8x7x6x5x4x3x2x1=3628800

100! contains about 160 digits and so on.

Character is who you are when no one is looking.

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**espeon****Real Member**- Registered: 2006-02-05
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lol yay!

Presenting the Prinny dance.

Take this dood! Huh doood!!! HUH DOOOOD!?!? DOOD HUH!!!!!! DOOOOOOOOOOOOOOOOOOOOOOOOOD!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

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**mathsyperson****Moderator**- Registered: 2005-06-22
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29. 3*10^5 * 3600 *24 * 365 ≈ 10^13 km

30. sin45 + cos45 = 1/√2 + 1/√2 = 2/√2 = 2√2/2 = √2

Why did the vector cross the road?

It wanted to be normal.

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**Devantè****Real Member**- Registered: 2006-07-14
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26. 216

27. Nope

28. 720

29. 1 light year = 9.4605284 × 10^12 km (simplified)

30. √2, depending on the form you want it in

Mathsyperson did it before me.

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**Devantè****Real Member**- Registered: 2006-07-14
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Oops, 29 should be:

1 kilometer = 1.05702341 × 10^-13 light years

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**ganesh****Moderator**- Registered: 2005-06-28
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Very well done, mathsyperson and Devante`.

Devante, the answer to #29 should be 10^13 kilometers, not 10^-13 kilometers. Also, 1 light year 10^13 kilometers, not the other way round.

Character is who you are when no one is looking.

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**Devantè****Real Member**- Registered: 2006-07-14
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OK, thanks for that. I always get muddled with light year conversion.

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**ganesh****Moderator**- Registered: 2005-06-28
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Devante`, a light year is 365x86140x3x10^8 approximately.

And a parsec is about 3.26 light years. A kiloparsec is 1,000 parsecs.

I am giving this information because all mathematicians are exepected to be very good in Astronomy.

31. How many kilometers is a mile approximately?

32. How many pounds is a kilogram approximately?

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**Devantè****Real Member**- Registered: 2006-07-14
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31. 1 mile = 1.609344 kilometers

32. 1 kilogram = 2.20462262 pounds

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**ganesh****Moderator**- Registered: 2005-06-28
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Devante`,

You are correct. Very well done.

Character is who you are when no one is looking.

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**ganesh****Moderator**- Registered: 2005-06-28
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33. How many zeros does a quintillion (US) contain?

34. What is special about the number 26?

Character is who you are when no one is looking.

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