Goi so hoc sinh lop 6A la a
(a thuoc N*,hoc sinh)
Theo de bai ta co: 
a:2           }=>a thuoc BC(2,3,4,6)
a:3               va a lon hon 35 hoac be hon 50
a:4
a:6
a lon hon 35 hoac be hon 50
2=2
3=3
4=2^2
5=5
BCNN(2,3,4,6)=2^2.3.5=60
BC(2,3,4,6)=B(60)={0;60;120;180...}
Vay khong co so nao thoa man vs yeu cau de bai