To determine how many times greater \( 1.008 \times 10^{-4} \) is than \( 4.2 \times 10^{-6} \), we can divide the two numbers:
\[ \text{Ratio} = \frac{1.008 \times 10^{-4}}{4.2 \times 10^{-6}} \]
This can be split into two parts: the coefficients and the powers of ten.
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Divide the coefficients: \[ \frac{1.008}{4.2} = 0.24 \]
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Subtract the exponents of 10 (using the property of exponents \( a^m \div a^n = a^{m-n} \)): \[ 10^{-4} \div 10^{-6} = 10^{-4 - (-6)} = 10^{-4 + 6} = 10^{2} \]
Now combine the results: \[ \text{Ratio} = 0.24 \times 10^{2} \] \[ = 24 \]
Thus, \( 1.008 \times 10^{-4} \) is 24 times greater than \( 4.2 \times 10^{-6} \).
In scientific notation, this can also be expressed as: \[ 2.4 \times 10^1 \]
So, the final answer is 24 or \( 2.4 \times 10^1 \).