Math Is Fun Forum

  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

#327 Re: Help Me ! » need help (ALGEBRAIC EXPRESSION) » 2007-01-12 02:19:15

Huh? The x values differ in each equation.

#328 Re: Puzzles and Games » Coolest » 2007-01-12 00:13:43

MathsIsFun wrote:

And the most boring one would be Q

I don't get it?

#329 Re: Jokes » green,pink ,yellow » 2007-01-11 22:27:00

Ah... this is a classic joke, I think I learnt it early in junior school.

#330 Re: Puzzles and Games » Coolest » 2007-01-11 20:58:29

Aww, I was only 6 letters out.

#331 Re: Guestbook » Something or other » 2007-01-11 20:37:53

Oh noes, somebody contradicted themselves sad

#332 Re: Guestbook » Something or other » 2007-01-11 20:27:56

Nope, nobody said anything.

#333 Re: Guestbook » Something or other » 2007-01-11 20:23:45

If somebody is a nobody then they are both a somebody and a nobody.

#334 Re: Guestbook » How Can They? » 2007-01-11 20:21:35

Would that be somewhere to the east of the City of Rats?

#335 Re: This is Cool » My ghost zombie convergency theorem! » 2007-01-11 19:58:36

But they will never exactly overlap one another, won't they?

#336 Re: Puzzles and Games » Bunny Game » 2007-01-11 19:55:25

It's still working fine for me

#337 Re: Introductions » Hello » 2007-01-11 16:10:04

Welcome Fried! Hope you enjoy our discussions. smile Like ur avi

#338 Re: Puzzles and Games » Coolest » 2007-01-11 05:37:43

i?
I think words starting or ending with 'I' sound cool. e.g. Icicle, Isotope, Gemini. Plus, it's the square root of -1, which is pretty kewl 2.

#339 Re: Help Me ! » Numbers which are divisible » 2007-01-10 22:44:20

If the x value's tenth's column is greater than or equal to 5, then is x rounded up, or is it always rounded down?

#340 Re: This is Cool » Genius Answer! 1/3 = » 2007-01-10 22:42:45

But... there is nothing missing. You can't say that the smallest possible number is missing because there is no such thing. The concept of infinity eliminates it. Infinity is so infinitely enormous that it, by brute force, vanquishes the smallest possible number.

#341 Re: Help Me ! » Numbers which are divisible » 2007-01-10 20:54:15

Oh...in my book it says

int(1000 ÷ 7) = 142

#342 Re: Help Me ! » Numbers which are divisible » 2007-01-10 20:21:34

This is, in a way related,

Does 'int' in int(x) stand for integer? If it does then is x rounded up or down?

#343 Re: Help Me ! » Numbers which are divisible » 2007-01-10 16:23:51

Thanks anyway pi man, I guess I got too used to doing it in one step, as I have learned to do with surds and trig to 'keep things accurate' smile

#344 Re: Maths Is Fun - Suggestions and Comments » Reaction Math with High Scores » 2007-01-10 16:20:37

It would be nice if we had a weekly or even daily high-score board to encourage more use of this mathematical tool. Otherwise, once the 'eternal' highscores have been set, usage may stagnate.

#345 Re: Help Me ! » Numbers which are divisible » 2007-01-10 16:18:11

Oh I see, 99 ÷ 4 = 24.75. Rounded down = 24. If I had seperately worked that out instead of using the combined sum that I used, I would have gotten 101 for my answer.

Thanks everyone.

#346 Re: Help Me ! » Numbers which are divisible » 2007-01-10 12:43:30

Oh i see, so if I'm looking for integers between x and y, where x > 0, then I simply have to add one.

But what if I had a question, to say, find between 14 and 18 (inclusive) all integers divisible by 4:
(18 ÷ 4) - (13 ÷ 4) = 1.25. If I were to round this up as has been suggested it would be incorrect.

#347 Re: Help Me ! » Numbers which are divisible » 2007-01-09 21:26:40

Oh noes it doesn't make any sense! dunno

#348 Re: Maths Is Fun - Suggestions and Comments » Reaction Math with High Scores » 2007-01-09 20:11:47

Yep, I usually find the first few questions are the slowest, and then the rest come much faster.

#349 Help Me ! » Numbers which are divisible » 2007-01-09 20:08:04

Toast
Replies: 16

Question
How many numbers between 100 and 500 (inclusive) are divisible by either 4 or 5?

The correct answer is 161 numbers. I am out by just one, with an answer of 160. Can someone please correct my working so it gives the correct answer. Thanks.

Solution:
Let n(A) = numbers divisible by 4
Since (500÷4)-(99÷4) = 100.25, there are 100 numbers between 100 and 500 divisible by 4.
i.e. n(A) = 100.

Let n(B) = numbers divisible by 5
Since (500÷5)-(99÷4) = 80.2, there are 80 numbers between 100 and 500 divisible by 5.
i.e. n(B) = 80.

To find n(A and B), notice that if a number is divisible by both 4 and 5, it must also be divisible by 20.
Since (500÷20)-(99÷4) = 20.05, there are 20 numbers between 100 and 500 divisible by 20.

Using n(A or B) = n(A) + n(B) - n(A and B) gives
         n(A or B) = 100 + 80 - 20
∴      n(A or B) = 160
Hence, there are 160 numbers between 100 and 500 divisible by either 4 or 5.

#350 Re: Help Me ! » Degrees » 2007-01-09 16:20:26

Well, seeing as complementary angles add up to 90 degrees and you have three times one of the angles, you can draw these algebraic conclusions:

1.

2.


re-arranging gives:

You can now use simultaneous equations to find angle A.

EDIT: Guess pi man beat me to it tongue

Board footer

Powered by FluxBB