Find the largest no that divides 630 and 940 leaving reminders 6 and 4 respectively
630 = 2^4•3•13+6
940 = 2^3•3^2•13+4
so, your number is 2^3•3•13 = 312
630 = 2*312+6
940 = 3*312+4
940 = 2^3•3^2•13+4
so, your number is 2^3•3•13 = 312
630 = 2*312+6
940 = 3*312+4