=IF(A1<=25.6,10,IF(AND(A1>25.6,A1<=26.1),8,IF(AND(A1>26.1,A1<=26.6),7,IF(AND(A1>26.6,A1<=27.1),6,IF(AND(A1>27.1,A1<=27.6),5,IF(AND(A1>27.6,A1<=28.1),4,IF(AND(A1>28.1,A1<=28.6),3,IF(AND(A1>28.6,A1<=29.1),2,IF(AND(A1>29.1,A1<=29.6),1,0)))))))))

there is your formula with ifs