Write the number -6.00009 x 10^7 in decimal notation without the use of exponents.

Step-by-step solution

1. 1

   Set the sign aside and read the exponent. The minus belongs to the coefficient. The exponent $+7$ is positive, so the number is large and the decimal point moves seven places right.

2. 2

   Count the digits you already have after the point. In $6.00009$ there are five digits after the point: $0,0,0,0,9$. Those five moves use up the existing digits, and the remaining $7-5=2$ moves must be filled with zeros.

3. 3

   Move the point five places, consuming the existing digits.

   $6.00009\to 60.0009\to 600.009\to 6000.09\to 60000.9\to 600009.$

   The interior zeros are placeholders and must all be carried — dropping them would give $69$ instead of $600009$.

4. 4

   Move the last two places, padding with zeros.

   $600009\to 6000090\to 60000900.$

5. 5

   Reattach the sign.

   $-6.00009\times 10^{7}=-60000900=-60{,}000{,}900.$

6. 6

   Check by multiplying directly. $6.00009\times 10{,}000{,}000=60{,}000{,}900$, and counting digits confirms the result has $8$ digits, consistent with a coefficient between $1$ and $10$ times $10^{7}$.