I need to design a form with many input fields in a row (around 15). What is the best approach to design such a layout. Shall I use table or Div? I can't attach a screenshot here but this is an application with lot of data being displayed in 15-18 small text boxes in a row (math value for each month) in a row.
I suppose it depends on the number of rows you intend to display. Not sure if 'modern' browsers are different but in the bad old days a table wouldn't display until all rows had been downloaded. So the user would see nothing for a few seconds and then the table would appear in a flash.
Definitely, I'll recommend table for many input field.
I would also recommend a table, not because there are many fields, but because it does indeed sound like tabular data (as @tedster suggests).
...a table wouldn't display until all rows had been downloaded.
Generally (these days) a table will start to display as the page begins to load and display progressively. However, whether there are certain edge conditions that can prevent a page from displaying until it has loaded in its entirety I'm not sure. (May be to do with calculating its final dimensions?)