If by planting you mean what gardeners and farmers do everyday, then the answer is yes, rational numbers come into it. A rational number is a one that be represented by two integers or whole numbers, one divided by the other. If, for instance, you were planting seeds in a row and they had to be a certain distance apart, you could work out how many seeds to plant in a row of a certain length. A farmer planting potatoes or strawberries in a field would want to know how many plants he could put into a field of a certain area. His calculations would involve rational numbers, and he would also need rational numbers to work out the cost of planting.