10 to the 6th power multiplied by what equals 10 to the 18th power

 
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            (10⁶) times (10^p) = 10¹⁸ .

When you multiply two numbers that have the same base
but different exponents, you just add the exponents.

So                                         6 + p = 18

Subtract 6 from each side:          p = 12 .

                 10⁶  x  10¹²  =  10¹⁸ .