DANIEL 3:19

Q: What does it mean that the furnace was heated to seven times its usual heat? The only way this would make sense is if the temperature was measured from absolute zero.

One possible answer is that seven times the usual amount of fuel was used. A more likely explanation is that this is one of many OT and NT examples where the number seven is used in its symbolic sense of “completion” or “perfection.” In other words, the oven was heated as hot as it could possibly get.