M = 1.2.3.4.5.6.7.8.9.10 = 1.2.3.2.2.5.2.3.7.2.2.2.3.3.2.5 = 1.28.34.52.7 chia hết cho 28
Đề: Chứng tỏ rằng
M=1.2.3.4.5.6.7.8.9.10
=1.2.3.2.2.5.2.3.7.2.2.2.3.3.2.5
=1.28.34.52.7 chia hết 28
M = 1.2.3.4.5.6.7.8.9.10 = 1.2.3.2.2.5.2.3.7.2.2.2.3.3.2.5 = 1.28.34.52.7 chia hết cho 28