Markup refers to the amount added to the cost price to cover overheads and profit. So for example a 50% markup on a $10 product would mean adding 50% of $10 onto the sale price. As fractions can be written as decimals (50% = 0.5) and we are adding on the amount of markup to the initial cost we can also phrase this as 10 x 1.5 = 15
For your question, the markup would become 1.1 and the initial cost is 2.7, remembering we must add 1 to the markup to cover the initial cost
= 21 x 21 x 21 x 21 x 21 x 5 = 20 420 505