Math Is Fun Forum

Chelsea

Member

Registered: 2005-06-16

Posts: 390

let the magician read your mind

Choose a four didgit number write that number backwards divide the smaller number by the larger number, keep your answer, now choose a nummber between 1 and 100, times your previous answer by the answer you just got, put a circle round a non zero number in other words put a circle round a number that isnt zero, type out your answer and put a * for the number that you put a circle around. for example if you got 145098 and you put a circle around the 5 it would be 14*098, remember to put a * for the number you put a circle around so the magician (me) dosnt know what that number is, reply to this topic as soon as possible, once you have replied i will tell you what that * number is! have fun and enjoy!!

---

Theres no other place like home or is there..............

JaneFairfax

Member

Registered: 2007-02-23

Posts: 6,868

Re: let the magician read your mind

Choose a four didgit number write that number backwards divide the smaller number by the larger number, keep your answer …

I think you made a mistake – I think you mean subtract the smaller number from the larger number. Also, I think the digits of the number must not all be the same (i.e. it must not be 1111, 2222, etc).

 

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: let the magician read your mind

Yes, I think you're probably right. That would certainly explain why only non-zero digits are allowed to be chosen. Otherwise, if a zero was chosen then the 'magician' wouldn't be able to tell whether it was a 0 or a 9.

Just doing this in my head, but I suspect that the trick still works in the more general case of allowing the person to rearrange the digits of their original number in any way they like, rather than just reversing them.

---

Why did the vector cross the road?
It wanted to be normal.