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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 422 · 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 6799 ÷ 71? (a) 970 (b) 97 (c) 9700
  2. 2.Best estimate of 1412 ÷ 62? (a) 240 (b) 24 (c) 2400
  3. 3.Best estimate of 3327 ÷ 61? (a) 55 (b) 5500 (c) 550
  4. 4.Best estimate of 939 ÷ 36? (a) 230 (b) 2300 (c) 23
  5. 5.√85 to 1 decimal place? (a) 9.0 (b) 9.3 (c) 9.1 (d) 9.2
  6. 6.Best estimate of 5568 ÷ 83? (a) 700 (b) 7000 (c) 70
  7. 7.Best estimate of 6054 ÷ 81? (a) 760 (b) 7600 (c) 76
  8. 8.Best estimate of 1764 ÷ 86? (a) 2000 (b) 20 (c) 200
  9. 9.√65 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 7.8 (d) 8.1
  10. 10.Best estimate of 2600 ÷ 59? (a) 4300 (b) 43 (c) 430
  11. 11.Best estimate of 732 ÷ 24? (a) 37 (b) 3700 (c) 370
  12. 12.√34 to 1 decimal place? (a) 5.8 (b) 6.0 (c) 5.9 (d) 6.1
  13. 13.Best estimate of 3178 ÷ 46? (a) 64 (b) 640 (c) 6400
  14. 14.Best estimate of 5776 ÷ 68? (a) 830 (b) 8300 (c) 83
  15. 15.√38 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.5 (d) 6.4
  16. 16.Best estimate of 475 ÷ 37? (a) 12 (b) 1200 (c) 120
  17. 17.√42 to 1 decimal place? (a) 6.5 (b) 6.7 (c) 6.8 (d) 6.6
  18. 18.√29 to 1 decimal place? (a) 5.4 (b) 5.2 (c) 5.3 (d) 5.5
  19. 19.√53 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.3 (d) 7.4
  20. 20.Best estimate of 6619 ÷ 72? (a) 950 (b) 9500 (c) 95
  21. 21.√92 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.8 (d) 9.6
  22. 22.Best estimate of 2925 ÷ 53? (a) 5900 (b) 59 (c) 590
  23. 23.√71 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.7 (d) 8.4
  24. 24.√26 to 1 decimal place? (a) 5.1 (b) 5.2 (c) 5.3 (d) 5.4
  25. 25.√96 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 10.0 (d) 9.7
  26. 26.√46 to 1 decimal place? (a) 6.8 (b) 6.6 (c) 6.9 (d) 6.7
  27. 27.Best estimate of 2786 ÷ 61? (a) 46 (b) 4600 (c) 460
  28. 28.Best estimate of 3073 ÷ 54? (a) 6100 (b) 61 (c) 610
  29. 29.Best estimate of 1284 ÷ 87? (a) 1400 (b) 14 (c) 140
  30. 30.Best estimate of 5413 ÷ 66? (a) 77 (b) 7700 (c) 770
  31. 31.√37 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.2 (d) 6.1
  32. 32.Best estimate of 4490 ÷ 82? (a) 56 (b) 560 (c) 5600
  33. 33.√40 to 1 decimal place? (a) 6.3 (b) 6.5 (c) 6.4 (d) 6.6
  34. 34.Best estimate of 4316 ÷ 62? (a) 7200 (b) 72 (c) 720
  35. 35.√43 to 1 decimal place? (a) 6.6 (b) 6.5 (c) 6.8 (d) 6.7
  36. 36.√21 to 1 decimal place? (a) 4.5 (b) 4.6 (c) 4.4 (d) 4.3
  37. 37.Best estimate of 568 ÷ 27? (a) 19 (b) 190 (c) 1900
  38. 38.√56 to 1 decimal place? (a) 7.5 (b) 7.2 (c) 7.4 (d) 7.3
  39. 39.Best estimate of 2574 ÷ 34? (a) 860 (b) 8600 (c) 86
  40. 40.Best estimate of 2322 ÷ 42? (a) 5800 (b) 58 (c) 580

Answer key

  1. 97
  2. 24
  3. 55
  4. 23
  5. 9.2
  6. 70
  7. 76
  8. 20
  9. 8.1
  10. 43
  11. 37
  12. 5.8
  13. 64
  14. 83
  15. 6.2
  16. 12
  17. 6.5
  18. 5.4
  19. 7.3
  20. 95
  21. 9.6
  22. 59
  23. 8.4
  24. 5.1
  25. 9.8
  26. 6.8
  27. 46
  28. 61
  29. 14
  30. 77
  31. 6.1
  32. 56
  33. 6.3
  34. 72
  35. 6.6
  36. 4.6
  37. 19
  38. 7.5
  39. 86
  40. 58

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