How do you constant a cell in excel after drag?

Answer 1

You use a mixed or an absolute reference. This is done by adding dollar symbols into a cell

A1 is a relative reference and will change when copied.

$A1 is a mixed reference, in which the row reference changes but the column reference does not.

A$1 is a mixed reference, in which the column reference changes but the row reference does not.

$A$1 is an absolute reference, so neither the column or row reference changes.

In most cases only a mixed reference is needed, though it is common to use an absolute reference. You lock the column reference when copying a formula across a row and you lock the row reference when you are copying a formula down a column. It is only on the very rare occasion that a formula is being copied both down and across, into a block, that an absolute reference is needed.