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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 436 · 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.√88 to 1 decimal place? (a) 9.4 (b) 9.2 (c) 9.1 (d) 9.3
  2. 2.Best estimate of 3922 ÷ 61? (a) 650 (b) 6500 (c) 65
  3. 3.Best estimate of 2516 ÷ 62? (a) 42 (b) 420 (c) 4200
  4. 4.Best estimate of 1799 ÷ 56? (a) 3000 (b) 300 (c) 30
  5. 5.√26 to 1 decimal place? (a) 4.8 (b) 5.0 (c) 4.9 (d) 5.1
  6. 6.√61 to 1 decimal place? (a) 7.7 (b) 8.0 (c) 7.8 (d) 7.9
  7. 7.√51 to 1 decimal place? (a) 7.1 (b) 7.4 (c) 7.3 (d) 7.2
  8. 8.Best estimate of 2196 ÷ 52? (a) 4400 (b) 44 (c) 440
  9. 9.Best estimate of 2683 ÷ 56? (a) 4500 (b) 450 (c) 45
  10. 10.Best estimate of 2669 ÷ 47? (a) 530 (b) 5300 (c) 53
  11. 11.Best estimate of 3992 ÷ 67? (a) 5700 (b) 570 (c) 57
  12. 12.√48 to 1 decimal place? (a) 7.0 (b) 6.7 (c) 6.9 (d) 6.8
  13. 13.Best estimate of 2850 ÷ 32? (a) 95 (b) 9500 (c) 950
  14. 14.Best estimate of 4891 ÷ 76? (a) 6100 (b) 610 (c) 61
  15. 15.Best estimate of 5361 ÷ 56? (a) 8900 (b) 890 (c) 89
  16. 16.√90 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.6 (d) 9.4
  17. 17.Best estimate of 2699 ÷ 38? (a) 670 (b) 6700 (c) 67
  18. 18.Best estimate of 4968 ÷ 56? (a) 8300 (b) 83 (c) 830
  19. 19.√96 to 1 decimal place? (a) 9.9 (b) 10.0 (c) 10.1 (d) 9.8
  20. 20.Best estimate of 1791 ÷ 28? (a) 60 (b) 600 (c) 6000
  21. 21.Best estimate of 5726 ÷ 62? (a) 95 (b) 9500 (c) 950
  22. 22.Best estimate of 4931 ÷ 88? (a) 5500 (b) 550 (c) 55
  23. 23.Best estimate of 6376 ÷ 89? (a) 710 (b) 71 (c) 7100
  24. 24.Best estimate of 4839 ÷ 71? (a) 69 (b) 690 (c) 6900
  25. 25.√40 to 1 decimal place? (a) 6.4 (b) 6.6 (c) 6.3 (d) 6.5
  26. 26.√67 to 1 decimal place? (a) 8.5 (b) 8.2 (c) 8.4 (d) 8.3
  27. 27.Best estimate of 6405 ÷ 69? (a) 9200 (b) 92 (c) 920
  28. 28.Best estimate of 915 ÷ 32? (a) 31 (b) 310 (c) 3100
  29. 29.Best estimate of 715 ÷ 42? (a) 1800 (b) 180 (c) 18
  30. 30.√24 to 1 decimal place? (a) 4.9 (b) 5.1 (c) 4.8 (d) 5.0
  31. 31.Best estimate of 1508 ÷ 26? (a) 50 (b) 500 (c) 5000
  32. 32.Best estimate of 1583 ÷ 34? (a) 5300 (b) 53 (c) 530
  33. 33.Best estimate of 1500 ÷ 68? (a) 210 (b) 21 (c) 2100
  34. 34.√85 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.4 (d) 9.1
  35. 35.Best estimate of 6294 ÷ 76? (a) 79 (b) 7900 (c) 790
  36. 36.Best estimate of 1459 ÷ 44? (a) 360 (b) 3600 (c) 36
  37. 37.Best estimate of 1493 ÷ 57? (a) 25 (b) 2500 (c) 250
  38. 38.√38 to 1 decimal place? (a) 6.5 (b) 6.4 (c) 6.3 (d) 6.2
  39. 39.√66 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 8.2 (d) 8.3
  40. 40.Best estimate of 2470 ÷ 62? (a) 41 (b) 410 (c) 4100

Answer key

  1. 9.4
  2. 65
  3. 42
  4. 30
  5. 5.1
  6. 7.8
  7. 7.1
  8. 44
  9. 45
  10. 53
  11. 57
  12. 6.9
  13. 95
  14. 61
  15. 89
  16. 9.5
  17. 67
  18. 83
  19. 9.8
  20. 60
  21. 95
  22. 55
  23. 71
  24. 69
  25. 6.3
  26. 8.2
  27. 92
  28. 31
  29. 18
  30. 4.9
  31. 50
  32. 53
  33. 21
  34. 9.2
  35. 79
  36. 36
  37. 25
  38. 6.2
  39. 8.1
  40. 41

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