30 deciliters he already has 1 liter.How many liters of milk will he need to buy?

• Americ: STEP 1:
  find number of liters in 30 deciliters
  
  1 deciliter= 0.1 liter
  
  multiply total number of deciliters (30) by liters in one deciliter (0.1).
  
  =30 * 0.1 liter
  =3 liters
  
  
  STEP 2:
  subtract 1 liter from step 1 answer because he already has one liter
  
  = 3 liters - 1 liter
  = 2 liters still needed
  
  
  ANSWER: He needs to buy 2 liters
  
  Hope this helps! :)