How to replace table cell values with cell value multiplied by 0.0254?

I want to look through the rows, find a specific text. If that text exists, then go to column 4 to 6 and replace those values by multiplying that value by 0.0254. How can I do that? I have this code but it doesn't work

num_rows = size(HabEx3P,1);
num_cols = size(HabEx3P,2);
for i = 1:1:num_rows
    if ~exist('GRID','var')
        for j = 4:1:6
            HabEx3P(:,j) = HabEx3P(:,j).*0.0254;
        end
    end
end

[Rik]

Your if-statement doesn't check for a text in your cell or table. And which is it: a cell or a table. The two data types are different in how they work. Unfortunately it is a bit difficult (and sometimes impossible) to use colon notation for cells.

Please give us a small example of HabEx3P, so we can help you write the code that works for your data.

[Hao Tang]

I also meant to use exist and not ~exist.

I've attached the HabEx3P matlab table

So to clarify, look in first column for the word GRID, then go to the 4th to 6th column and replace that Value with Value*0.0254

For some reason, I always get an error 'Undefined operator '*' for input arguments of type 'table'

Eventually, the table will have lots of unique words like GRID, but if I can get just replacing values with GRID values working then the rest should be straightforward

[Peter Perkins]

Please see my answer to your nearly identical question in another post you made yesterday:

https://www.mathworks.com/matlabcentral/answers/383763-finding-category-string-in-table-and-converting-values?s_tid=prof_contriblnk