Three digit numbers in which the middle one is a perfect square are formed using the digits 1 to 9 Their sum is

Explanation

Here, unit digit and hundred digits can be any of the `9` digits.

Ten`'`s digits can be any of the three numbers `1,4 and 9`.

`:.` Total numbers possible `= 9**3**9 = 243`

`:.` Sum of unit digits ` = 243/9(1+2+3+4+5+6+7+8+9) = 27**45 = 1215`

Sum of ten`'`s digits `= 243/3**10**(1+4+9) = 81**140 = 11340`

Sum of hundred`'`s digits `= 243/9**100**(1+2+3+4+5+6+7+8+9) = 81**4500 = 121500`

:. Total sum `= 121500+11340+1215 = 134055`

So, the required sum is `134055`.