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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 939 · 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 4287 ÷ 51? (a) 860 (b) 8600 (c) 86
  2. 2.Best estimate of 914 ÷ 21? (a) 46 (b) 460 (c) 4600
  3. 3.Best estimate of 905 ÷ 49? (a) 18 (b) 1800 (c) 180
  4. 4.√62 to 1 decimal place? (a) 8.2 (b) 7.9 (c) 8.1 (d) 8.0
  5. 5.Best estimate of 4355 ÷ 56? (a) 73 (b) 7300 (c) 730
  6. 6.Best estimate of 5611 ÷ 63? (a) 940 (b) 94 (c) 9400
  7. 7.√37 to 1 decimal place? (a) 6.4 (b) 6.1 (c) 6.3 (d) 6.2
  8. 8.Best estimate of 1061 ÷ 32? (a) 3500 (b) 35 (c) 350
  9. 9.√58 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.8 (d) 7.5
  10. 10.√27 to 1 decimal place? (a) 5.0 (b) 5.1 (c) 4.9 (d) 5.2
  11. 11.√75 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.6 (d) 8.9
  12. 12.√69 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.2 (d) 8.3
  13. 13.√66 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 7.9 (d) 8.0
  14. 14.Best estimate of 1635 ÷ 43? (a) 4100 (b) 410 (c) 41
  15. 15.√38 to 1 decimal place? (a) 6.3 (b) 6.2 (c) 6.1 (d) 6.0
  16. 16.√89 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.5 (d) 9.3
  17. 17.Best estimate of 2297 ÷ 81? (a) 2900 (b) 290 (c) 29
  18. 18.√35 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 6.2 (d) 6.1
  19. 19.Best estimate of 1742 ÷ 44? (a) 440 (b) 4400 (c) 44
  20. 20.√76 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.4 (d) 8.5
  21. 21.Best estimate of 1453 ÷ 32? (a) 480 (b) 48 (c) 4800
  22. 22.Best estimate of 437 ÷ 28? (a) 150 (b) 15 (c) 1500
  23. 23.Best estimate of 3063 ÷ 69? (a) 4400 (b) 440 (c) 44
  24. 24.√55 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.5 (d) 7.4
  25. 25.Best estimate of 5629 ÷ 61? (a) 9400 (b) 94 (c) 940
  26. 26.Best estimate of 824 ÷ 32? (a) 27 (b) 270 (c) 2700
  27. 27.√65 to 1 decimal place? (a) 8.0 (b) 8.2 (c) 8.1 (d) 8.3
  28. 28.Best estimate of 1068 ÷ 41? (a) 270 (b) 2700 (c) 27
  29. 29.√59 to 1 decimal place? (a) 7.5 (b) 7.4 (c) 7.7 (d) 7.6
  30. 30.√74 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.5 (d) 8.6
  31. 31.Best estimate of 595 ÷ 32? (a) 20 (b) 2000 (c) 200
  32. 32.Best estimate of 2680 ÷ 86? (a) 3000 (b) 30 (c) 300
  33. 33.Best estimate of 4628 ÷ 74? (a) 6600 (b) 660 (c) 66
  34. 34.Best estimate of 2745 ÷ 42? (a) 6900 (b) 69 (c) 690
  35. 35.Best estimate of 1253 ÷ 47? (a) 2500 (b) 25 (c) 250
  36. 36.Best estimate of 5134 ÷ 59? (a) 8600 (b) 86 (c) 860
  37. 37.Best estimate of 2665 ÷ 72? (a) 3800 (b) 380 (c) 38
  38. 38.Best estimate of 6270 ÷ 87? (a) 70 (b) 700 (c) 7000
  39. 39.√71 to 1 decimal place? (a) 8.3 (b) 8.1 (c) 8.4 (d) 8.2
  40. 40.Best estimate of 715 ÷ 23? (a) 36 (b) 360 (c) 3600

Answer key

  1. 86
  2. 46
  3. 18
  4. 7.9
  5. 73
  6. 94
  7. 6.1
  8. 35
  9. 7.6
  10. 5.2
  11. 8.7
  12. 8.3
  13. 8.1
  14. 41
  15. 6.2
  16. 9.4
  17. 29
  18. 5.9
  19. 44
  20. 8.7
  21. 48
  22. 15
  23. 44
  24. 7.4
  25. 94
  26. 27
  27. 8.1
  28. 27
  29. 7.7
  30. 8.6
  31. 20
  32. 30
  33. 66
  34. 69
  35. 25
  36. 86
  37. 38
  38. 70
  39. 8.4
  40. 36

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