List 3-digit numbers that leave remainder 4 when divided by 7, then check for remainder 3 when divided by 6.

• Numbers = 7k + 4. For 3-digit: k ≥ 14 (7×14+4 = 102)
• Try: 102 ÷ 6 = 17 r 0 ✗
• Try 109 ÷ 6 = 18 r 1 ✗
• Try 116 ÷ 6 = 19 r 2 ✗
• Try 123 ÷ 6 = 20 r 3 ✓
• 123 ÷ 7 = 17 r 4 ✓

The smallest possible 3-digit number is 123.
Final Answer: 123