The KJV generally approximates the idea here, but it isn't that close to the Greek. It also minimizes the debt here to "improve" the lesson by making it more extreme. The debt owed is significant. Because the size of the debt is minimized (a problem corrected in many more modern translations), we miss an important point of the story: that the original servant could have collected this debt earlier, but if he had done so, he would have had to pay it to his master. Once he is free and can keep the money, collecting it becomes a much higher priority.
Again, this verse teaches us something about the differences between the modern view of slavery and slavery in Christ's time. These men were enslaved because of their debts, but these debts were not minor amounts, especially at the time. A "slave" of a king could be much better off in terms of lifestyle and future expectations than a freeman, especially one without property. Slaves, even slaves because of their debts, could have a great deal of money or assets, as this part of the story expresses.
Christ's Words in Matthew as a Guide to 40 Days of Prayer.