We have moved the decimal point 7 places
    93,000,000 became 9.3 x 107
The exponent tells us how many places we
have moved the decimal point. If you want
to return to the original number just move the
decimal point 7 places to the right and fill in
the empty places with zeros.
93,000,000.  became 9.3000000 x 107  which
becomes 9.3 x 107  dropping the zeros
following the 3.
Please note that in a problem such as 4005000
the zeros between  the 4 and 5 are not dropped!
4005000 becomes 4.005000 x 106  which
becomes 4.005 x 10 6

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