I have some data that represents what is below in a column of my spreadsheet:

3125
3125 3120
3130 3125
3125
3115 3125

I have a filter on my sheet and when I do a custom filter on that column and
use contains 3125, I do not get the results in row 1 and 4 above, but just
the other ones that have 3125 with another number (rows 2,3, & 5). Am I
doing something wrong, or does anyone know why that is happening?

Thanks in advance