Bonjour,
1)
18 = 2 x 3 x 3
24 = 2 x 2 x 2 x 3
30 = 2 x 3 x 5
42 = 2 x 3 x 7
49 = 7 x 7
196 = 2 x 2 x 7 x 7
252 = 2 x 2 x 3 x 3 x 7
455 = 5 x 7 x 13
546 = 2 x 3 x 7 x 13
840 = 2 x 2 x 2 x 3 x 5 x 7
2)
180/126 = (2 x 2 x 3 x 3 x 5) / (2 x 3 x 3 x 7) = [(2 x 5) x (2 x 3 x 3)] / [7 x (2 x 3 x 3)] = (18 x 10) / (18 x 7) = 10/7
585/1 275 = (3 x 3 x 5 x 13) / (3 x 5 x 5 x 17) = [(3 x 5) x (3 x 13)] / [(3 x 5) x (5 x 17)] = (15 x 39) / (15 x 85) = 39/85
360/252 = (2 x 2 x 2 x 3 x 3 x 5) / (2 x 2 x 3 x 3 x 7) = [(2 x 2 x 3 x 3) x (2 x 5)] / [2 x 2 x 3 x 3) x 7] = (36 x 10) / (36 x 7) = 10/7
32 670/792 = (2 x 3 x 3 x 3 x 5 x 11 x 11) / (2 x 2 x 2 x 3 x 3 x 11) = [(2 x 3 x 3 x 11) / (3 x 5 x 11)] = [(2 x 3 x 3 x 11) x (2 x 2)] = (198 x 165) / (198 x 4) = 165/4
17 303/1 859 = (11 x 11 x 11 x 13) / (11 x 13 x 13) = [(11 x 13) / (11 x 11)] / [(11 x 13) x 13] = (143 x 121) / (143 x 13) = 121/13.
