N°1.
1) 4 × 13 × 25 = (4 × 25) × 13 = 100 × 13 = 1300
2) 125 × 17 × 8 = (125 × 8) × 17 = 1000 × 17 = 17000
3) 4 × 24 × 5 = (4 × 5) × 24 = 20 × 24 = 480
4) 50 × 236 × 2 = (50 × 2) × 236 = 100 × 236 = 23600
N°2.
1) 12 × 3a = 36a
2) 8x × 7 = 56x
3) 27 × b × 5 = 135b
4) 6a × 7b = 42ab
5) 35x × 23y = 805xy
6) 4a × 9 × b × 2 × c = 72abc