Increasing values by a percentage

If cell B2 has your value you want to increase and cell C2 has the percentage (i.e., the number 0.005 with the cell formatted as a percentage so it displays as 0.5%, or you typed 0.5% into the cell which will do this) then in another cell use the formula

=B2*(1+C2)

100% to stay where you started + 0.5% increase.

Example:

60 increased by 4% = 60 + 4% increase = 60 + 4%*60 = 60*(1 + 4%) = 60*(100% + 4%) = 60*(104%)