(;AB[ij]AB[ii]AB[ih]AB[jg]AB[kg]AB[lg]AB[mg]AB[nh]AW[mi]AW[li]AW[ki]AW[ni]AB[oi]AB[oh]AB[ng]AB[nj]AB[mj]AB[lj]AB[kj]AW[oj]AW[ok]AW[ol]AW[nl]AW[ml]AW[ll]AW[kl]AW[jl]AW[jk]AW[ik]LB[jj:A]C[How big is A?FORCE]LB[gg:1]LB[gh:2]LB[gi:3]LB[gj:4]LB[gk:5]LB[gl:6]AP[goproblems] (;W[gj];B[gi]AW[jj]AB[ji]LB[kk:1]LB[kh:2]LB[lk:3]LB[lh:4]LB[mk:5]LB[mh:6]LB[jj:A]C[Well done! Wherether white choses to use 1,3,5 as ko threats or not, black will still have to capture the 4 white stones. So he has 4x2(prioners+ter under them) + 1(the ter at k12) = 9 moku. If black went at A he'd have 4x2(prioners+ter under them) + 5(k11, k12,l12,m12,n12 ter) = 13 moku. The difference is 4. (As karmaGfa mentions in the comments - 'black in A is gote while white in A is sente for the capturing race. ')RIGHT]) (;W[gg]C[The correct anwser is 4. Please chose it for an explanation.]) (;W[gh]C[The correct anwser is 4. Please chose it for an explanation.]) (;W[gi]C[The correct anwser is 4. Please chose it for an explanation.]) (;W[gk]C[The correct anwser is 4. Please chose it for an explanation.]) (;W[gl]C[The correct anwser is 4. Please chose it for an explanation.]))