Final answer:
The calculator display of 1.78E12 represents the number 1.78 times 10 to the 12th power, a form of scientific notation for large numbers.
Step-by-step explanation:
When Charlee's calculator shows 1.78E12, this is a way of displaying numbers in scientific notation. The 'E' stands for exponent, which means that the number should be interpreted as 1.78 multiplied by 10 raised to the 12th power, or 1.78 x 1012. Scientific notation is often used for very large or very small numbers to make them easier to read and work with. For large numbers, such as in this instance, it simplifies the reading of the number which would otherwise have many trailing zeros (1,780,000,000,000).