If my Cost Price is 16.56 and I want to have a 50% Profit margin how much should be the Selling price? Can you please give me an standrard computation?

Cost x 1.50

If you're marking up 50% then you have 150% of the cost.

i.e. cost is 100%, + the extra 50%, then selling price = 150% of
the original cost.

Move the decimal over twice and you have "x 1.50".