what should I enter to get the cell to do this?

[CCCexcel]

I want to format a cell to use this formula =A2*B2+D2+H2+K2+P2+R2+V2+J2+N2 if the value in Q2 is less than 11, I want the cell to choose this formula =A2*B2+D2+H2+K2+P2+S2+V2+J2+N2 if the value of Q2 is >=11 and <=20, I want the cell to choose this formula =A2*B2+D2+H2+K2+P2+T2+V2+J2+N2 if the value of Q2 is >=21 and <=30, I want the cell to choose this formula =A2*B2+D2+H2+K2+P2+U2+V2+J2+N2 if the value of Q2 is >=31 and <=40

[shg]

There are some holes in your conditions, but maybe

=A2*B2 + D2 + H2 + K2 + P2 + V2 + J2 + N2 + INDEX(R2:T2, MATCH(Q2, {-99,11,21,31}))

[FDibbins]

Or perhaps this (longer)....
=A2*B2+D2+H2+K2+P2+V2+J2+N2+IF(AND(Q2<=40,Q2>30),U2,IF(Q2>20,T2,IF(Q2>10,S2,R2)))