Having issues averaging empty cells

[Doon1]

Hello All,
I think a picture to begin with would best help me to describe the issue I'm having.
Capture1.JPG

As you can see I am adding selected groups of averaged numbers. If there is no data in one or two cells of the averaged three cell group there is no problems. Yet if there is no data in all three cells of a group then the formula returns #DIV/0!. There will be times that there is no date in any of the three cells of one or more groups.
I've been searching for and trying different options. All to no avail. Does anyone know if what I want to do is possible?
Thank you.
John

Edit. As an example: There may be a week when my students will not be turning in any "Do Now" work all week because they are working on a special project. I don't want their overall weekly grade to be effected by putting in a number that represents work that has not been assigned. If I put in a 0 it will reduce their grade, if I put in 100 in will inflate their grade.

[tim201110]

function IFERROR

[Doon1]

Thank you. That does seem to be a very useful function. Unfortunately it exposed another problem in my formula. I can't have a value returned for that group if there is no entry as it will change the overall percentage in the total column. I need to get better at this.

[Doon1]

So I'm thinking that the best way (read easiest for an amateur) to do this would be to add a hidden cell at the end of each 3 cell group with this formula =IFERROR(AVERAGE(G3:I3),"")
Then my total column formula would use the average of those hidden cells.

TIM, YOU DA MAN!
I added the hidden columns and then wrote the total formula as =AVERAGE(F3,J3,N3,R3) and it worked perfectly.
Thanks again.