Assume that the gross national debt initially is equal to $3 trillion and the federal government then runs a deficit of $300 billion

Step 1: Start with the initial gross national debt of $3 trillion.

Step 2: Subtract the deficit of $300 billion from the initial debt.
$3 trillion - $300 billion = $2.7 trillion
Step 3: The new gross national debt after running a $300 billion deficit is $2.7 trillion.

To determine the new gross national debt after running a deficit, we need to add the deficit amount to the initial debt.

Step 1: Convert the deficit amount to trillion dollars
Since the initial debt is given in trillion dollars, we need to convert the deficit of $300 billion to trillion dollars.
1 trillion dollars = 1,000 billion dollars
So, $300 billion = $300 billion / $1,000 billion = 0.3 trillion dollars.

Step 2: Add the deficit amount to the initial debt
The new gross national debt is equal to the initial debt plus the deficit amount.
New debt = Initial debt + Deficit
New debt = $3 trillion + $0.3 trillion
New debt = $3.3 trillion.

Therefore, the new gross national debt after running a deficit of $300 billion is $3.3 trillion.