1. number sense if you know 12 × 24 = 288, how can you fi nd 1.2 × 2.4?
2. number sense is the product 1.23 × 8 greater than or less than 8? explain.
copy the problem and place the decimal point in the product.
3. 1.7 8
× 4.9
8 7 2 2
4. 9.2 4
× 0.6 8
6 2 8 3 2
5. 3.7 5
× 5.2 2
1 9 5 7 5 0
how many decimal places are in the product?
6. 6.17 × 8.2 7. 1.684 × 10.2 8. 0.053 × 2.78
with homework
2.5 exercises
use base ten blocks or an area model to fi nd the product.
9. 2.1
× 1.5
10. 0.6
× 0.4
11. 0.7
× 0.3
12. 2.7
× 2.3
multiply. use estimation to check your answer.
13. 4.8
× 7
14. 6.3
× 5
15. 7.19
× 16
16. 0.87
× 21
17. 1.95
× 11
18. 5.89
× 5
19. 3.472
× 4
20. 8.188
× 12
21. 100 × 0.024 22. 19 × 0.004 23. 0.0038 × 9 24. 10 × 0.0093
error analysis describe and correct the error in the solution.
25. 0.0045
× 9
4.05 ✗
26. 0.32
× 5
0.160 ✗
27. moon the weight of an object on the moon is about 0.167 of
its weight on earth. how much does a 180-pound astronaut
weigh on the moon?
28. bamboo a bamboo plant grows about 1.25 feet each day. find
the growth in one week.
29. nails a fi ngernail grows about 0.1 millimeter each day. how
much does a fi ngernail grow in 30 days? 90 days?