420×29=12180;
4 2 0
×
2 9
3 7 8
8 2 1 2 1 8 0
305×24=7320;
3 0 5
2 4
1 2 2 0
6 1 0 7 3 2 0
504÷7=72;
7 2
7
5 0 4
4 9 1 4
1 4 0
100÷6=16…4;
1 6
6
1 0 0
6 4 0
3 6 4