His question asks for a number answer. Acceptable answers include whole numbers, integers (negative numbers), and decimal values. (These questions will normally require you to do calculations by hand or with a computer before you enter a final answer.) In special cases, you may need to enter DNE for "Does not exist", oo for infinity, or -oo for negative infinity.

Enter exact values. Do not round unless the directions state otherwise.
Enter the number 6.2839