No, they're absolutely necessary. The "actual answer", is actually a lie. If you give the "actual answer" you are implying a certain level of certainty that you do not have. It's like ...2.6 * 1.3
With sigfigs, you'd give 3.4, but the "actual answer" is 3.38. However, when you give 3.38, you are implying a level of certainty that you do not have. What if the measurement instruments were only accurate to two sigfigs(not unlikely)? Then you would be implying that your measuring capability was greater and more precise than it was, when the answer could actually have been anywhere from 3.1875 - 3.5775. Therefore, 3.38 is a false statement. 3.4, states that you do not know up to a little bit here and there, from around 3.2 to 3.6. However, 3.38 implies that you know somewhere between 3.36 to 3.40...