See QUARTILE
In Google Sheets, the function QUARTILE.INC is used to calculate the quartiles of a dataset. The function takes two arguments:
Data: This is the range of cells or array that contains the dataset for which you want to calculate the quartiles. Quart: This is a number between 0 and 4 that represents the quartile you want to calculate. For example, quart = 1 calculates the first quartile (25th percentile), quart = 2 calculates the second quartile (50th percentile or median), and quart = 3 calculates the third quartile (75th percentile).
The QUARTILE.INC function uses the "inclusive" method to calculate quartiles. This means that it includes the quartile values in the dataset when determining the boundaries for each quartile.
For example, if you have a dataset of 10 numbers, the first quartile will be the value at the 2.5th position (inclusive), the second quartile will be the value at the 5th position (inclusive), and the third quartile will be the value at the 7.5th position (inclusive).