1. Stating the problem: Calculate the value of the first expression $-9 \div 1$. 2. Formula and rules: Division of integers follows the rule that dividing by 1 leaves the number unchanged, and dividing by a negative number changes the sign of the quotient. 3. Calculation: $$-9 \div 1 = -9$$ 4. Explanation: Dividing $-9$ by $1$ means how many times $1$ fits into $-9$. Since $1$ fits $-9$ times, the answer is $-9$. Final answer: $-9$