Subtract the decimal from the whole number.<br><br>
• 9 − 3.1<br>
• Ones: 9 − 3 = 6<br>
• Tenths: 0 − 1 needs regrouping<br>
• 9 = 8 ones + 10 tenths<br>
• 3.1 = 3 ones + 1 tenth<br>
• Ones: 8 − 3 = 5<br>
• Tenths: 10 − 1 = 9<br>
• 9 − 3.1 = 5.9<br><br>
Final Answer: 5.9