The 4 digit positive numbers from 5512 are:
[tex]\mleft\lbrace5512,5521,1255,2155,1552,2551,1525,2515,5215,5125,5152,5251\mright\rbrace[/tex]The sum of all the numbers will be:
[tex]43329[/tex]So the last three digits of the sum is 329.
Another way to do it is to add the three digits of the 4 digit numbers as shown below:
[tex]\begin{gathered} 512+521+255+155++552+551+525+515+215+125+152+251 \\ =4329 \end{gathered}[/tex]So the last digits is 329.
