((((((((((((828,829,830,831)))))))))))))))

=1/2*4/3=2/3 =5/12*3/2=5/8 =4/9*3/2=2/3 =8/15*5/4=2/3 ----------------- =5/3*2/5=2/3 =12/1*5/6=10 =15/4*4/5=3 =45/4*2/9=5/2=2 1/2 -------------------- =5/12*2/5=3/4 =1/4*2/1=1/2 =7/4*8/21=2/3 =1/3*9/12=3/2=1 1/2 --------------------------- =3/1*2/1=6 =3/4*2/3=1/2 =11/12*6/11=1/2 =25/3*9/5=15