1: 5*3. 14 is approximately equal to 5*3= 15 (cm) or 5*3. 14 is approximately equal to 10*3=30 (cm).

15*3. 14 is approximately equal to 15*3=45 (cm) or 15*3. 14 is approximately equal to 20*3=60 (cm).

2: 4.5 * 30 is approximately equal to 5*30= 150 (pieces).

3: 5.5*200 is approximately equal to 10*200=2000 (grams).

10.5*2000 is approximately equal to 1 1*2000=22000 (g).