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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 942 · 40 questions
TalentJR

How to do it in your head (Guess, divide, average): Division: round the divisor to the nearest ten and find the closest multiple of it. Square root: guess the nearest whole root, then divide the number by your guess. Average the guess and the answer of the division, and round to 1 decimal place.

NameDateTime takenScore ___ / 40
  1. 1.Best estimate of 1277 ÷ 44? (a) 32 (b) 3200 (c) 320
  2. 2.Best estimate of 4373 ÷ 46? (a) 87 (b) 870 (c) 8700
  3. 3.√58 to 1 decimal place? (a) 7.5 (b) 7.4 (c) 7.7 (d) 7.6
  4. 4.Best estimate of 2323 ÷ 56? (a) 390 (b) 39 (c) 3900
  5. 5.√94 to 1 decimal place? (a) 9.7 (b) 10.0 (c) 9.9 (d) 9.8
  6. 6.√48 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 6.7 (d) 6.6
  7. 7.Best estimate of 5816 ÷ 72? (a) 8300 (b) 83 (c) 830
  8. 8.√40 to 1 decimal place? (a) 6.5 (b) 6.3 (c) 6.2 (d) 6.4
  9. 9.Best estimate of 1606 ÷ 38? (a) 4000 (b) 400 (c) 40
  10. 10.√86 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.0 (d) 9.3
  11. 11.√84 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.2 (d) 9.1
  12. 12.√70 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.4 (d) 8.1
  13. 13.√89 to 1 decimal place? (a) 9.2 (b) 9.5 (c) 9.4 (d) 9.3
  14. 14.√69 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 8.0 (d) 8.3
  15. 15.√74 to 1 decimal place? (a) 8.5 (b) 8.7 (c) 8.4 (d) 8.6
  16. 16.Best estimate of 3417 ÷ 82? (a) 430 (b) 43 (c) 4300
  17. 17.√98 to 1 decimal place? (a) 9.9 (b) 10.1 (c) 9.8 (d) 10.0
  18. 18.Best estimate of 2356 ÷ 32? (a) 7900 (b) 79 (c) 790
  19. 19.√63 to 1 decimal place? (a) 8.2 (b) 7.9 (c) 8.1 (d) 8.0
  20. 20.Best estimate of 1493 ÷ 24? (a) 750 (b) 75 (c) 7500
  21. 21.√79 to 1 decimal place? (a) 9.2 (b) 8.9 (c) 9.0 (d) 9.1
  22. 22.Best estimate of 4242 ÷ 86? (a) 470 (b) 47 (c) 4700
  23. 23.Best estimate of 4860 ÷ 71? (a) 690 (b) 6900 (c) 69
  24. 24.√55 to 1 decimal place? (a) 7.2 (b) 7.4 (c) 7.1 (d) 7.3
  25. 25.Best estimate of 1316 ÷ 28? (a) 440 (b) 4400 (c) 44
  26. 26.Best estimate of 2425 ÷ 26? (a) 810 (b) 81 (c) 8100
  27. 27.Best estimate of 1946 ÷ 72? (a) 280 (b) 2800 (c) 28
  28. 28.√23 to 1 decimal place? (a) 4.7 (b) 4.8 (c) 4.9 (d) 5.0
  29. 29.Best estimate of 5328 ÷ 74? (a) 760 (b) 76 (c) 7600
  30. 30.Best estimate of 2342 ÷ 27? (a) 7800 (b) 78 (c) 780
  31. 31.Best estimate of 4408 ÷ 86? (a) 4900 (b) 490 (c) 49
  32. 32.√21 to 1 decimal place? (a) 4.7 (b) 4.6 (c) 4.4 (d) 4.5
  33. 33.Best estimate of 1947 ÷ 66? (a) 2800 (b) 28 (c) 280
  34. 34.Best estimate of 6375 ÷ 87? (a) 710 (b) 71 (c) 7100
  35. 35.Best estimate of 5692 ÷ 72? (a) 8100 (b) 81 (c) 810
  36. 36.Best estimate of 6138 ÷ 84? (a) 77 (b) 770 (c) 7700
  37. 37.√34 to 1 decimal place? (a) 5.9 (b) 5.7 (c) 6.0 (d) 5.8
  38. 38.Best estimate of 2438 ÷ 26? (a) 810 (b) 8100 (c) 81
  39. 39.Best estimate of 4430 ÷ 64? (a) 7400 (b) 74 (c) 740
  40. 40.Best estimate of 2950 ÷ 43? (a) 74 (b) 740 (c) 7400

Answer key

  1. 32
  2. 87
  3. 7.6
  4. 39
  5. 9.7
  6. 6.9
  7. 83
  8. 6.3
  9. 40
  10. 9.3
  11. 9.2
  12. 8.4
  13. 9.4
  14. 8.3
  15. 8.6
  16. 43
  17. 9.9
  18. 79
  19. 7.9
  20. 75
  21. 8.9
  22. 47
  23. 69
  24. 7.4
  25. 44
  26. 81
  27. 28
  28. 4.8
  29. 76
  30. 78
  31. 49
  32. 4.6
  33. 28
  34. 71
  35. 81
  36. 77
  37. 5.8
  38. 81
  39. 74
  40. 74

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