Resolved: We can just use Q_1 in the formula instead of indirect function. So why using Indirect function?

Hi rajaonarivony!

Thanks for reaching out.

Named ranges help you organize the data of your sheet in an efficient way. 

Then, sometimes in computations we need to refer to many cells and, analytically speaking, it might become harder to trace where the numbers used in the formulas come from. In that case, INDIRECT() gives you a good indication on where are some of the values in a formula derived from.

Also, and more importantly, if you want to apply the same formula for several sets/subselections of data in your sheet, instead of changing the entire formula for each subselection, you can just change a referenced cell in it.

Hope this helps.
Best,
Martin

You are very welcome!
Kind regards,
Martin