math question

[Travis]

What is the lowest number that you can multiply times 9 and the sum of the answer does not equal 9?

Example
123
X9
1107 (added together=9)

Note (may have to add more than once)
Travis

 

[kityuser]

simple


0


(you didn't say natural number)
Steve

 

[Calpol]

11 x 9 = 99

:-k

 

[StevieB]

11 x 9 = 99

Steve.

 

[NickWelford]

11 x 9 = 99

:-k

Not so - you have to add the two 9's together also = 18 then add = 9

 

[Calpol]

Aah I see, very cunning...

 

[MikeG.]

Apart from zero, every multiple of 9 produces a number with digits that add up to 9...........or at least they do eventually. If you keep adding the digits of the answers you will eventually get back to 9.

For example:

87x9=783

7+8+3=18

1+8=9

or

1441x9=12,969

1+2+9+6+9=27

2+7=9

The more challenging question would be "Prove the general case".

Mike

 

[yo_chuci]

isn't this one of those questions where the answer is you can't

seem to remember something bout this before. it might always add up to nine

 

[kityuser]

The more challenging question would be "Prove the general case".

Mike

probably out of my depth as its a few years since my university maths lectures, however I seem to remember "proof by induction" would be the way to go for this one.


why is zero not counted? I claim the first correct answer to the stated question 8)

Steve

 

[MikeG.]

why is zero not counted? I claim the first correct answer to the stated question 8)
Steve

IMO zero is counted and you win the prize..........

However, I didn't set the question :wink:

Proof by induction would require you to demonstrate that a first case is true, and that the next case (n+1) is also true. I'm hoping you have more time on your hands than me!!!!

Mike

BTW........your location. Kent/Essex???? You live on the Thames?

 

[big soft moose]

BTW........your location. Kent/Essex???? You live on the Thames?

he's squatting on the dartford bridge

 

[MikeG.]

he's squatting on the dartford bridge

Well, he wants to be careful, then, that some Chinese pensioner doesn't come along and push him into the river!