Multiplication
5x3
15
Factors of 5
1,5
420 + 360
980
3,896 - 2, 984
912
9x7
63
Factors of 6
1, 2, 3, 6
653 + 986
639
9,102 - 6,340
2,762
5x20
100
Factors of 9
1,3,9
666 + 762
1428
763 - 499
264
80x40
3200
Factors of 21
1, 3, 7, 21
45 + 987
1032
8,475 - 609
7,866
90x200
18000
Factors of 18
1, 2, 3, 6, ,9,18
3908 + 4566
8474
7,341 - 5,180
2,161