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?
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.
#### 198