When the number is greater than 1

1. Count the digits from the left up to the decimal (whether it's a visible
   or an invisible decimal).  Subtract 1.  That will be the exponent of 10.

2. Write down the first digit, followed by a decimal and then all the rest of
   the digits. (You can erase any trailing zeros unless told otherwise)

3.  After that write " ×10 " and then place the exponent from step 1 above
    the 10.


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Let's go through it step by step:

5,890,000,000,000 is greater than 1
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1. Count the digits from the left up to the decimal (whether it's a visible
   or an invisible decimal).  Subtract 1.  That will be the exponent of 10.

5,890,000,000,000 has an invisible decimal at the right end,  There are
   
13 digits.  Subtract 1.  That gives 12, So 12 will be the exponent of 10.
--------------------------------------
2. Write down the first digit, followed by a decimal and then all the rest of
   the digits.  (You can erase any trailing zeros unless told otherwise)

5.890000000000  Then we erase the trailing zeros.

5.89
--------------------------------------
3.  After that write " ×10 " and then place the exponent from step 1 above
    the 10.

5.89×1013


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Edwin