LEARN ABOUT IT
In some problems you only need an answer that is close to correct. You can estimate. In other cases, you need an exact answer. Decide which method to use by what you are going to do with the answer.
1. Gerald is on duty in the watchtower. It is 10:37 PM. He wants to stop at an inn on the way home. At what time shall he tell his friends he will arrive at the inn?
Gerald does not need to arrive at the inn at an exact time.
He can estimate the time needed.
2. Joan is practicing for a rowing competition. She wants to know how much greater her trial time is than the course record time of 23 minutes, 9 seconds.
Joan needs to know exactly how many seconds faster she must go to beat the record.
Joan needs to know her exact trial time.