
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
Guangyuan City focuses on the development strategy of "$1345$" and the "14th Five-Year Plan", firmly grasping the key project construction "bull's nose". The "List of Key Projects in Guangyuan City in 2023" includes a total of 300 projects, among which there are 10 ecological and environmental protection projects, with a planned total investment of about 45 billion yuan. Express the data $45$ billion in scientific notation as ______.

Present the answer in LaTex format: \boxed{Your answer}
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