The total liters of juice he has is 5 jars x 2 liters/jar = <<5*2=10>>10 liters of juice
Then he needs to convert this amount to milliliters: 10 liters x 1000 milliliters/liter = <<10000=10000>>10,000 milliliters
He can fill up to 10,000 ml / 250 ml/glass = <<10000/250=40>>40 glasses
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