answersLogoWhite

0


Best Answer

Every time you subtract the first and second digits of the 2-digit number you chose, it comes up with a multiple of 9.

For example, 25-2-5=18. 18 is a multiple of 9.

So is: 75-5-7=63. 63 is a multiple of 9.

On the Regifting Robin gift list, all of the numbers that are a multiple of 9 have the same gift.

For example, let's say you did: 99-9-9=81.

The number you got will always be a multiple of 9, so all the multiples of 9 get the same gift:

So,

18=labelmaker

27=labelmaker

36=labelmaker

45=labelmaker

and so on and so forth. The gift changes every time to make it more convincing. Labelmaker is an example of a gift. It won't be labelmaker every time.

So the question should be why is it that we always end up with multiples of 9?

Let the number N = Ones+ 10x + 100y + 1000z + ... (example : 574 = 4 + 7*10 + 5*100 )

Its digits are w, x, y, z, ... So the sum of the digits is w + x + y + z + ... = S.

So, N - S = D = (ones-ones) + (10x-x) + (100y-y) + (1000z -z) + ... = 9x + 99y + 999z + ... = 9 (x + 11y + 111z + ...)

So, N - S is a multiple of 9.

But, there is more:

Once again let N = ones + 10x + 100y + 1000z + ...

We want to prove that, if the sum of its digits, S is divisible by 9, then so is the number, N, and conversely.

If S is divisible by 9, then S = 9p. Now add the number D to this, calculated above. S + D = 9p + D. But we saw previously that D itself is a multiple of 9, so D = 9q. Hence, S + D = 9p + 9q = 9(p+q) = 9r, say. But then, S + D is nothing but N. So N = 9r, which is what we wnted to show?

The converse is proved by starting with N = 9r and subtracting D to yield S = 9(r-q) = 9p,say.

See the Related Link for more info on the workings of Regifting Robin.

User Avatar

Wiki User

โˆ™ 2011-02-09 17:34:53
This answer is:
User Avatar
Study guides

Jobs

19 cards

Why is customer service so important

Gross profit and net profit

Does law require that employers offer health benefits to any of its employees

What is the purpose of a union

โžก๏ธ
See all cards
4.15
โ˜†โ˜…โ˜†โ˜…โ˜†โ˜…โ˜†โ˜…โ˜†โ˜…
33 Reviews

Add your answer:

Earn +20 pts
Q: How does Regifting Robin work?
Write your answer...
Submit
Still have questions?
magnify glass
imp
People also asked