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50 - Digit Number (Posted on 2003-11-15) Difficulty: 3 of 5
A number of 50 digits has all its digits equal to 1 except the 26th digit. If the number is divisible by 13, then find the digit in the 26th place.

See The Solution Submitted by Ravi Raja    
Rating: 3.3333 (6 votes)

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re: correction | Comment 22 of 39 |
(In reply to correction by Richard)

Of course, why didn't I think of that!? :-s
Thanks for your effort of typing in everything you know about modulus numbers...but, nope, unfortunately I cannot start to use them to solve puzzles as I still haven't the foggiest idea what you're going on about! I was OK until you starting putting equations in. Stating what % meant, I was averagely happy with - but then you started using equations, it didn't make any sense! To you or experts, maybe - but to a complete beginner these things take time - so, I'd advise you not to give up your day job! Hopefully it isn't a teacher!
I understand that teaching over the internet is difficult at the best of times, but seriously...am I supposed to understand (10^n)%11=((-1)^n)%m?????? And no, we don't do ANY of that now! GCSE mathematics is very simple. A-level mathematics and Further Mathematics are trickier and involve differentiation, integration and numerous functions...including hyperbolic and inverse hyperbolic functions and their derivatives (this bit *only* features on the Further Mathematics course)

Back to your explanation...just a handy teaching hint...read back over your previous message - in the viewpoint of a person who knows *nothing* about modulo....can you see that half-way through, you shoot *too* quickly into multiple equations that would confuse any poor soul? I think I speak for the majority of youngsters...if not all - but I'm sure there's some university students out there thinking how silly I am - but, not knowing as much means I can spot a good teacher a mile off - which is why I want to become a mathematics teacher, as I know where problems lie, and how to explain things thoroughly - thoroughly enough that they understand what is going on step by step. If part one of something is a bit 'cloudy', then extending that even further is even mroe cloudy, e.g. a student may not remember that "2a" means "2 x a" but infacts thinks it's "a x a". When you talk about "2a x 2a = 4aa" (or "4 a^2" or "4 a squared") - it will confuse him beyond belief, even though it seems simple to him. Just that *one* part of an equation, and it confuses him. Going on to show him the, almost simple Quadratic formula would make the student faint!
See where I'm coming from? Sorry that you tried so hard yet I didn't understand, I feel quite bad now as you've tried hard to explain things and I still haven't understood...but never mind, I'll save you the effort of teaching me now...unless you're preapred to explain in FULL...or of course if you have MSN messenger, where you could explain in full and I can question parts as we go along! For now, I'll leave you, and prepare for my television recordings in under 2 weeks time - and, yes, it does involve some maths, but only mental arithmetic! :-)
  Posted by Kirk on 2003-11-22 18:39:12

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