1. **State the problem:** Multiply 123 by 89. 2. **Formula used:** Multiplication of two numbers is done by repeated addition or using the standard multiplication algorithm. 3. **Step-by-step multiplication:** $$123 \times 89$$ Break down 89 as $80 + 9$: $$123 \times (80 + 9) = 123 \times 80 + 123 \times 9$$ Calculate each part: $$123 \times 80 = 9840$$ $$123 \times 9 = 1107$$ 4. **Add the partial products:** $$9840 + 1107 = 10947$$ 5. **Final answer:** $$123 \times 89 = 10947$$ This method uses distributive property to simplify multiplication.