Primary school: 2*3+24/4= 12
Junior high school: 16 0.5 * 3 = 12.
High school: the diameter of the circle x 2+y 2 = 36 is 12.
University: The integral of f(x)=6x in the interval is 12.
Socialization: There are 100- 100 months in a year.
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I don't know, ask again; Satisfied, good luck driving!