Grade 4 - Progress in Mathematics

Estimate with Compatible Numbers

Estimate the quotient.

10. 9
     9  5  11. 6
     4  3  12. 2
     8  7  13. 5
     3  8  14. 4
     9  2 


11. 4
     5  9  1  16. 7
     8  6  2  17. 3
     9  4  7  18. 2
     8  1  5 


12. 6
     2  7  5  20. 9
     4  6  7  21. 8
     7  4  4  22. 5
     3  4  2 


13. 7
     2  4  3  9  24. 4
     3  6  2  2  25. 3
     1  7  2  9  26. 9
     5  6  4  9 


14. 2
    $ 4 .9 4  28. 3
    $ 6 .4 2  29. 5
    $ 17 .5 0  30. 4
    $ 28 .5 8 

Compatible numbers are numbers that are easy to compute mentally.

Estimate: 53 
 6 Estimate: 223 
 7

Divide: 53
 6 Divide: 223
 7

Think: 54 
 6  9 Think: 210 
 7  30

So, 53
6 is about 9. So, 223
7 is about 30.

Estimate the quotient. Use compatible numbers.

Write the compatible numbers you used to estimate the quotient.

31. 55
    8 32. 46
    6 33. 362
    5 34. 178
    3


32. 4
     2  9  36. 5
     3  3  37. 8
     2  6  38. 3
     1  1  39. 7
     4  0 


33. 3
     6  1  41. 4
     8  4  42. 2
     6  3  43. 5
     5  6  44. 3
     9  1 


34. 7
     2  8  5  46. 5
     1  6  1  47. 6
     5  2  4  48. 9
     4  7  2  49. 7
     5  5  1 

Use division facts to find nearby numbers that are compatible.

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