Answer:
2,400,000,000,000
Explanation:
2.4 x 10^12 means that the decimal point is moved 12 places to the right (hence the power of 12)
So by moving the decimal point 12 times you get this: 2,400,000,000,000
The reason why there are only 11 zeroes is because the 4 was a decimal place to the right of 2, thus losing a zero.