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#201 Re: Puzzles and Games » Self-Referential Aptitude Test » 2010-05-20 20:19:44

I won't coerce you but lemme guess... has it got something to do with anagrams?
I found a lewd one with the answers wink

#202 Re: Help Me ! » Summation » 2010-05-20 20:13:44

soha wrote:

Look at any term, say 3(7[sup]2[/sup]), and you'll observe that 7 = (2×3+1)

observe... T[sub]1[/sub] = 1(3)[sup]2[/sup] = 1(2×1+1)[sup]2[/sup]

T[sub]2[/sub] = 2(5)[sup]2[/sup] = 2(2×2+1)[sup]2[/sup] etc


We can say that T[sub]n[/sub]= n(2×n+1)[sup]2[/sup]


NOTE: Its true that you'll have to guess it.
Most of the times, they will always be easy (of the form n(an+b)) in the questions given in your textbooks and exams.
Curve fitting is another idea that you just don't need in your school.

#203 Re: Puzzles and Games » Perfect Squares.. » 2010-05-20 19:54:32

gurthbruins wrote:

- not a job that appeals to me, I regret...

........sigh......

old fermat  what

#204 Re: Puzzles and Games » Perfect Squares.. » 2010-05-20 19:52:03

TheDude wrote:

Specifically, only the squares of 4 through 50 are eligible, and it's a pretty simple matter to brute force.  As it happens there is exactly one such pair of squares - 13 & 14.

That's really tricky but now i got it (after checking the maximum difference possible between two numbers who's Last Two digits are same, may be in different orders)!! up

TheDude wrote:

In short, the numbers you are looking for are the squares of 10, 12, 13, 14, 20, 30, 38, 40, 50, 60, 62, 70, 80, 88, and 90, and any multiple of 100 plus any of those numbers except 13 and 14.

Your last sentence again holds a Lot of Information! Thx!!

TheDude wrote:

For the second method you should note that in multiplication the final two digits of the product are decided solely by the final two digits of the multiplicands.  Again you can simply brute force numbers from 4 to 99 and check by hand.  For squares found using this method you can add any multiple of 100 and it will still work.  Aside from the obvious multiples of 10, the squares that fall under this category are 12, 38, 62, and 88.

I'll try and see if some sort of Algebraic method can help give those numbers rolleyes


Earlier i was wondering if big perfect square xxxxxxxxxab exists such that xxxxxxxxxba is also perfect square (a,b≠0). Now i see that such a number can't be any greater than 7744 wink

Thanks dude smile

#205 Re: Puzzles and Games » Joan's telephone number & my YOB » 2010-05-20 19:33:05

Hi again phrontister!

part-A was quite easy but charming wink

part-B? I'm already panicked by your repetitive instructions to use a computer to solve it.
Nonetheless, I'll give a try!!

#207 Re: Puzzles and Games » Perfect Squares.. » 2010-05-20 06:26:37

I learned C when in Second year of my Four year Engg course and my sis (who has command over more than 7 different programming languages) tried to teach me CPP some years back.
I still have a fair idea of C but 've forgotten sleep most of the other things coz of not using them for 3 years!
Although I like your proposition yet i'd like to know how to work it out using Algebra? smile

#208 Puzzles and Games » Perfect Squares.. » 2010-05-20 04:45:17

ZHero
Replies: 10

I just wanted to find all the Perfect Squares (except 0, 1, 4 and 9 tongue) such that if their Unit's and Ten's digits are interchanged, the resulting number is again a Perfect Square!

I know a few

.

How can I find ALL SUCH Perfect Squares??

#209 Re: Help Me ! » Newton's laws » 2010-05-20 01:40:50

Right again wink

by using this value of v, you'll get a[sub]s[/sub] ∼ 734.41 m/s[sup]2[/sup] instead of 729 m/s[sup]2[/sup].

#210 Re: Help Me ! » Newton's laws » 2010-05-20 01:29:09

that's correct!!

but only to a few decimal places!

that's coz you've taken v = 10.8 ∼ 10.8444

you should get Force ∼ 73.441 ∼ 73.5 with v = 10.84

#211 Re: Help Me ! » Newton's laws » 2010-05-20 01:19:12

soha wrote:




use v[sup]2[/sup] - u[sup]2[/sup] instead of v[sup]2[/sup] + u[sup]2[/sup] and plz make it 0.08 m instead of 0.8 m!!!  smile

#212 Re: Help Me ! » Newton's laws » 2010-05-20 01:11:36

soha wrote:

by solving it in the method which you explained first , i got
first v=10.8

next a =6.4
F=0.64N
, which is the wrong answer as per the textbook.

were did i go wrong?

use 10.8[sup]2[/sup] - 0[sup]2[/sup] = 2a[sub]s[/sub]0.08

this should give you a[sub]s[/sub]=734.41 m/s[sup]2[/sup]

can you tell me what exactly did you do?

#213 Re: Help Me ! » Newton's laws » 2010-05-20 00:54:40

SHORTCUT:

From the Law of Conservation of Energy....

mgh = (1/2)mv[sup]2[/sup] = work done by the opposing force = Force × distance covered

where m = mass (0.1 kg)

g = acceleration due to gravity (9.8 m/s[sup]2[/sup]

h = height of fall (6 m)

0.1×9.8×6 = Force×0.08

Force = (0.1×9.8×6)÷0.08

#214 Re: Puzzles and Games » Add 13 more and post it forever. » 2010-05-20 00:34:04

6357 <--- cetchup

6370

(1+3=4) digit Prime numbers with 6, 3, 7, 0.

3067 is a Prime number.

3607 is a Prime number.

6037 is a Prime number.

6073 is a Prime number.

6703 is a Prime number.

7603 is a Prime number.

#215 Re: Help Me ! » Newton's laws » 2010-05-20 00:31:38

Oh yeahh.... I have just edited my previous post!

#216 Re: Help Me ! » Newton's laws » 2010-05-20 00:21:50

soha wrote:

I have many such physics related doubts. Can I post them here at Mathsis fun???

While solving the first part by your method, do we get

is that correct?

Just a small error...
its ∼ 10.8 (m/s)

plz recheck the decimal point.....  touched

And why of course YES! You can always post your maths/physics problems here (MIF should agree with me here  neutral).

Somebody will always be here to help!! up

#217 Re: Puzzles and Games » Add 13 more and post it forever. » 2010-05-19 22:04:25

6344

6344[sup]th[/sup] Prime number is 63317

There's your evil number again Tig yikes

#218 Re: Help Me ! » Newton's laws » 2010-05-19 21:55:58

Hi soha...

Part-1: To calculate the Velocity of the stone just before it starts penetrating the sandy bed (v).

Velocity of the stone when it just starts penetrating the sandy bed can be calculated using v[sup]2[/sup] - u[sup]2[/sup] = 2a[sub]g[/sub]s

where v = final velocity of the stone (when it just starts penetrating the sandy bed)

u = initial velocity of the stone = 0 m/s (coz nothing's mentioned except that it just falls)

a[sub]g[/sub] = acceleration due to gravity = 9.8 m/s[sup]2[/sup]

s = distance covered = 6 m (distance covered while falling.. given)

Part-2: To calculate the Acceleration due to sandy bed (a[sub]s[/sub]).

Now use the relation v[sup]2[/sup] - u[sup]2[/sup] = 2a[sub]s[/sub]s

here v = final velocity of the stone = 0 m/s (coz it comes to rest after penetrating 8cm)

u = initial velocity of stone (when it just starts penetrating the sandy bed) = the value of v rolleyes that you will get from Part-1.

a[sub]s[/sub] = acceleration due to sandy bed

s = 8 cm = 0.08 m (distance penetrated.. given)

Part-3: To calculate the Force exerted by the sandy bed (F).

Now use F = M × a[sub]s[/sub]

where F = force exerted by sandy bed (you have to find out) up

M = mass of stone = 0.1 kg (given)

a[sub]s[/sub] = acceleration due to sandy bed = value of a[sub]s[/sub] that you got from Part-2.



I'm not gonna solve it fully for you sleep

Hopefully that helps...

Let know if you still have any problems dizzy

#220 Re: Jokes » Silly Questions Funny Answers! » 2010-05-19 20:14:42

Hi Tigeree!

wink that's cool cool

the tring tring one can be explained but lets leave that part right now tongue

and chuck wud be chafed if he comes to know of you  dizzy

#221 Re: Puzzles and Games » Self-Referential Aptitude Test » 2010-05-19 01:25:06

I can wait till then (just don't forget wink ok)

And i'd like to know what's special bout the answer according to you and mathsyperson??
Might be that I couldn't discover it.... sad

#223 Re: Puzzles and Games » Add 13 more and post it forever. » 2010-05-18 23:09:06

6292 = (1 + 3) × (11) × (11) × (13)

#224 Re: Euler Avenue » How to remember numbers? » 2010-05-18 22:39:23

Its a nice search engine.

I tried 169 and it says I forgot something tongue

Doesn't work quite good for Large numbers though
e.g. I tried 16553 and it returns the following searches...
Taj ul-Alam
and
Seth Gilliam
etc which don't prove to be any help, whatsoever, to me!?

#225 Re: Jokes » Silly Questions Funny Answers! » 2010-05-18 18:18:48

only Chuck Norris (better known at "The Chuck" <-- pronounced as "Da Chuck" or "Chucky") can do this...

Q: What is the e-mail id of Chuck Norris??
A:

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