Question 758234: Please help me solve this?
My Question,
Find all two digit numbers n such that N+2 is also a two digit number and the digit sum of N+2 is less than the digit sum of N
My working out?
N+2= 2 digit number which has to be bigger than the sum of N+2
Answer by josmiceli(19441)   (Show Source):
You can put this solution on YOUR website! It looks like  is as high as you can go
because if  , then  ,
which is 3 digits
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I could also state a rule that for any pair of 2-digit numbers,
 and  , if the 10s digit does not change when
you go from one to the other, then the sum of the digits
of  will always be greater than the sum of the
digits of .
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That means that if the digits of are  ( for tens )
and  ( for units ), then only in the cases where
 and  will he digit sums of
be less than the digit sums of .
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So, the required number pairs are:
18, 20
19, 21
28, 30
29, 31
38, 40
39, 41
48, 50
49, 51
58, 60
59, 61
. . . . .
88, 90
89, 91
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