We can express 7103 as 7×(50−1)51=7[50k−1]
True
7103 = 7 ×(49)51
= 7 ×(50−1)51
7 ×(50−1)51 = 7[51C0(50)51−51C1(50)50+51C2(50)49............51C50(50)1−51C51]
7 ×(50−1)51 = 7[51C0(50)51−51C1(50)50+51C2(50)49............51C50(50)1−1]
51C0(50)51−51C1(50)50+51C2(50)49............51C50(50)1 is a multiple of 50.We will replace it with 50k
7 ×(50−1)51=7[50k−1]