=SUM - sum of the cells selected or the value entered.
=IF - (sorry, can't explain it well) States if the logical question (thingy) is true or not.
=MIN - selects the least value of the value entered or among the cells selected.
=MAX - selects the greatest value among the value's entered or among the cells selected
=AVERAGE - finds the average of the values entered or of the cells selected.
EXAMPLES
Try it on MS Excel and you'll see. ☺
=SUM (A9,A5,B6,F7,E8,F9,C2,D4)
=SUM (2419,2134,321)
=IF(A9<100,"True","False")
=MIN(92,32,54,45,64)
=MIN(B9,B4,C3,A5)
=MAX(32,42,63,64,75)
=MAX(A9,B2,B5)
=AVERAGE(84,98,86)
=AVERAGE(A9,B9,C9,D9)
I hope it help. ☺