1. The problem is to understand and express the number 3.91938417383707E+28 in a more readable form. 2. The notation 3.91938417383707E+28 means $3.91938417383707 \times 10^{28}$. 3. This is scientific notation, where the number before the E is the coefficient and the number after E is the exponent of 10. 4. To write it out fully, move the decimal point 28 places to the right. 5. The number is very large, approximately 39,193,841,738,370,700,000,000,000,000. 6. This is useful for representing very large numbers compactly.