1. The problem is to multiply 35 by 15. 2. We can write this as $35 \times 15$. 3. Multiply 35 by 10: $35 \times 10 = 350$. 4. Multiply 35 by 5: $35 \times 5 = 175$. 5. Add the two results: $350 + 175 = 525$. 6. Therefore, $35 \times 15 = 525$.