The barrel lost 220 * 10 / 100 = <<220*10/100=22>>22 liters before anyone noticed.

So, 220 – 22 = <<220-22=198>>198 liters are left in the barrel.

# Answer

198
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
A 220-liter barrel has a small leak. It lost 10% of its contents before anyone noticed. How many liters are left in the barrel?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
198
A 220-liter barrel has a small leak. It lost 10% of its contents before anyone noticed. How many liters are left in the barrel?
train