AE lay tong cua cac con so o giai db ngay thu 4 hang tuan tru cho 8 duoc bao nhieu thi lay tong (-8) do lam 2 cham de nuoi tu thu 5- chu nhat
_ tong (tru8) nho hon 10 thi con 19s
+ tong (tru 8) lon hon 10 thi lay 2s do lam 2 cham duoc 36s
vd thu 4 ngay 4/11 db 16921 ta co 1+6+9+2+1 bang 21 lay 21-8 bang 11 ta co cham 1 nuoi tu thu 5- chu nhat tuan nay
( tong tru 8 ma ra 12 thi co c 1,2 )
_ tong (tru8) nho hon 10 thi con 19s
+ tong (tru 8) lon hon 10 thi lay 2s do lam 2 cham duoc 36s
vd thu 4 ngay 4/11 db 16921 ta co 1+6+9+2+1 bang 21 lay 21-8 bang 11 ta co cham 1 nuoi tu thu 5- chu nhat tuan nay
( tong tru 8 ma ra 12 thi co c 1,2 )