(2,3)(5,9)(7,13)(9,);5-2=3,9-3=6,6÷3=2;7-5=2,13-9=4,4÷2=2;
9-7=2,2×2=4,13+4=17,=17
(18,10)(10,6)(20,11)(?,4);18-10=8,10-6=4,8÷4=2;20-10=10,11-6=5,10÷5=2;
11-4=7,7×2=14,20-14=6,=6
2,10,10,66,26,218,50,514,82,1008,( 122 ),( 1768 );
(2,3)(5,9)(7,13)(9,);5-2=3,9-3=6,6÷3=2;7-5=2,13-9=4,4÷2=2;
9-7=2,2×2=4,13+4=17,=17
(18,10)(10,6)(20,11)(?,4);18-10=8,10-6=4,8÷4=2;20-10=10,11-6=5,10÷5=2;
11-4=7,7×2=14,20-14=6,=6
2,10,10,66,26,218,50,514,82,1008,( 122 ),( 1768 );