Level $1$

As you work each question, you are building your skills.

Write the number in decimal notation without the use of exponents.

$-2\mathrm{.}000009{10}^8$

A number is written in scientific notation when it is expressed in the form $a{10}^n,$ where the absolute value of a is greater than or equal to $1$ and less thar

What is the value of $a?$

$a=$