Is an estimate calculated by a rounding algorithm.

Usually, the stem will explain the exact number of digits. If it is accurate to ten digits, 49 1 is about 490. According to the rounding algorithm, if the number of digits is 4 or less, such as 362, it is about 360. If the number of digits is greater than 5, such as 3 17, it is about 320. You can ask my geek math teacher if you have any questions.