2 transform of the old number

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圖片參考：https://s.yimg.com/rk/HA05107138/o/1373788124.png

不是
主要是:
two 2 transformation
19=1+2x9=19 a=1 b=9 a+2xb=
28=2+2x8=18 a=2 b=8
three 2 transformation
114=11+2x4=19 a=11 b=4
four 2 transformation
1109=110+2x9=128 a=110 b=9
完全不明所以
是澳洲year 7 的數學推理題
見過未

2014-03-18 10:55:19 補充：
主要是用 a+2b= 這條equation
b是最後數目字
a是前面數目字
總之是不切實際的數目難題
不懂也罷

2014-03-20 15:44:28 補充：
thank you....

2014-03-20 19:06:51 補充：
我不知道有空將整条問題上傳

2014-03-20 20:45:36 補充：
a numberis transformed by deleting its units digit and adding the remaining number to double the units digit which was deleted. the new number is called the 2-transform of the old number. for example,the 2-transform of 2014 is 201+2x4=209. continuing this process,

2014-03-20 20:48:28 補充：
we see that the 2-transform of 209 is 20+2x9=38, the 2-transform of 38 is 3+2x8=19, and the 2-transform of 19 is 1+2x9=19.

2014-03-20 20:51:29 補充：
a. show that the 2-transform of every number less than 19 is also less than 19.
b. find the next starting number after 2014 for which the 2-transform process gives 19.

2014-03-20 20:55:04 補充：
c. show that every 2-digit number changes to 19 or less after at most two 2-transformations.
d. find the smallest number that needs exactly three 2-transformations to give 19.
真的不知說什麼

2014-03-24 10:31:31 補充：
good and thanks to all

odd number?

2014-03-17 19:51:23 補充：
19 那個明白

28=18
114=19
1109=128
不明白

2014-03-19 20:50:28 補充：
現在我明白你說什麼了～
但我不明白你問什麼～

你想問這個 transformation 的數學公式？

f(x) = [ x / 10 ] + 2 * ( x mod 10 )

2014-03-20 18:58:21 補充：
是這個意思嗎？

你們學了這些 functions?

ceiling, floor, modulus, ...

2014-03-20 20:03:00 補充：
OK, 你可以先按延長發問, 那麼帖子就不會被刪掉~

2014-03-22 22:39:16 補充：
This is a very good question.

Let me invite some experts......

2014-03-23 16:29:59 補充：
Thank you very much!

Excellent Question, Excellent Answer!

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