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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 42 · 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 2315 ÷ 49? (a) 46 (b) 460 (c) 4600
  2. 2.Best estimate of 4469 ÷ 71? (a) 64 (b) 640 (c) 6400
  3. 3.√50 to 1 decimal place? (a) 7.4 (b) 7.2 (c) 7.3 (d) 7.1
  4. 4.Best estimate of 1453 ÷ 39? (a) 3600 (b) 360 (c) 36
  5. 5.Best estimate of 1096 ÷ 76? (a) 14 (b) 140 (c) 1400
  6. 6.Best estimate of 1568 ÷ 31? (a) 52 (b) 5200 (c) 520
  7. 7.Best estimate of 2219 ÷ 26? (a) 7400 (b) 740 (c) 74
  8. 8.Best estimate of 3873 ÷ 56? (a) 6500 (b) 65 (c) 650
  9. 9.Best estimate of 682 ÷ 46? (a) 14 (b) 140 (c) 1400
  10. 10.√53 to 1 decimal place? (a) 7.6 (b) 7.5 (c) 7.3 (d) 7.4
  11. 11.√30 to 1 decimal place? (a) 5.8 (b) 5.5 (c) 5.7 (d) 5.6
  12. 12.√59 to 1 decimal place? (a) 7.7 (b) 7.4 (c) 7.5 (d) 7.6
  13. 13.Best estimate of 2999 ÷ 36? (a) 7500 (b) 75 (c) 750
  14. 14.√23 to 1 decimal place? (a) 4.9 (b) 5.0 (c) 4.8 (d) 5.1
  15. 15.Best estimate of 2399 ÷ 74? (a) 34 (b) 340 (c) 3400
  16. 16.Best estimate of 2627 ÷ 64? (a) 440 (b) 4400 (c) 44
  17. 17.√61 to 1 decimal place? (a) 7.7 (b) 7.9 (c) 7.8 (d) 8.0
  18. 18.Best estimate of 4493 ÷ 64? (a) 7500 (b) 750 (c) 75
  19. 19.√35 to 1 decimal place? (a) 5.8 (b) 5.9 (c) 5.7 (d) 5.6
  20. 20.Best estimate of 4082 ÷ 46? (a) 82 (b) 820 (c) 8200
  21. 21.Best estimate of 3367 ÷ 82? (a) 42 (b) 420 (c) 4200
  22. 22.√98 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.8 (d) 9.9
  23. 23.Best estimate of 2888 ÷ 66? (a) 4100 (b) 410 (c) 41
  24. 24.√32 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.4 (d) 5.7
  25. 25.√63 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 7.8 (d) 8.1
  26. 26.√34 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 5.7 (d) 5.8
  27. 27.Best estimate of 6246 ÷ 82? (a) 780 (b) 7800 (c) 78
  28. 28.√24 to 1 decimal place? (a) 4.9 (b) 5.0 (c) 4.8 (d) 4.7
  29. 29.Best estimate of 1272 ÷ 49? (a) 2500 (b) 250 (c) 25
  30. 30.Best estimate of 5441 ÷ 81? (a) 68 (b) 680 (c) 6800
  31. 31.Best estimate of 1291 ÷ 32? (a) 4300 (b) 43 (c) 430
  32. 32.√82 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 8.8 (d) 9.1
  33. 33.Best estimate of 4737 ÷ 57? (a) 7900 (b) 79 (c) 790
  34. 34.Best estimate of 3067 ÷ 42? (a) 7700 (b) 77 (c) 770
  35. 35.Best estimate of 2222 ÷ 36? (a) 560 (b) 56 (c) 5600
  36. 36.√94 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.7 (d) 9.5
  37. 37.Best estimate of 4416 ÷ 61? (a) 7400 (b) 74 (c) 740
  38. 38.√66 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.0 (d) 8.1
  39. 39.Best estimate of 947 ÷ 28? (a) 3200 (b) 32 (c) 320
  40. 40.√52 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.4 (d) 7.1

Answer key

  1. 46
  2. 64
  3. 7.1
  4. 36
  5. 14
  6. 52
  7. 74
  8. 65
  9. 14
  10. 7.3
  11. 5.5
  12. 7.7
  13. 75
  14. 4.8
  15. 34
  16. 44
  17. 7.8
  18. 75
  19. 5.9
  20. 82
  21. 42
  22. 9.9
  23. 41
  24. 5.7
  25. 7.9
  26. 5.8
  27. 78
  28. 4.9
  29. 25
  30. 68
  31. 43
  32. 9.1
  33. 79
  34. 77
  35. 56
  36. 9.7
  37. 74
  38. 8.1
  39. 32
  40. 7.2

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