5 • 4 = 20
5 • 40 = 200
3 • 8 = 24
3 • 80 = 240
2 • 9 = 18
2 • 90 = 180
5 • 1 = 5
5 : 1 = 5
20 • 10 = 200
20 : 10 = 2