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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 115 · 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 917 ÷ 32? (a) 3100 (b) 310 (c) 31
  2. 2.√38 to 1 decimal place? (a) 6.2 (b) 6.0 (c) 6.3 (d) 6.1
  3. 3.Best estimate of 1413 ÷ 36? (a) 3500 (b) 350 (c) 35
  4. 4.√87 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.1 (d) 9.0
  5. 5.√41 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.5 (d) 6.2
  6. 6.Best estimate of 2197 ÷ 86? (a) 24 (b) 2400 (c) 240
  7. 7.√98 to 1 decimal place? (a) 9.9 (b) 9.6 (c) 9.8 (d) 9.7
  8. 8.Best estimate of 7458 ÷ 81? (a) 9300 (b) 93 (c) 930
  9. 9.Best estimate of 776 ÷ 32? (a) 2600 (b) 260 (c) 26
  10. 10.Best estimate of 5616 ÷ 72? (a) 8000 (b) 80 (c) 800
  11. 11.Best estimate of 5598 ÷ 62? (a) 93 (b) 930 (c) 9300
  12. 12.Best estimate of 959 ÷ 47? (a) 1900 (b) 190 (c) 19
  13. 13.√50 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 7.4 (d) 7.3
  14. 14.Best estimate of 2515 ÷ 59? (a) 4200 (b) 42 (c) 420
  15. 15.√69 to 1 decimal place? (a) 8.5 (b) 8.2 (c) 8.3 (d) 8.4
  16. 16.√45 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.5 (d) 6.4
  17. 17.√63 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.2 (d) 8.1
  18. 18.Best estimate of 3491 ÷ 72? (a) 5000 (b) 500 (c) 50
  19. 19.Best estimate of 2634 ÷ 39? (a) 660 (b) 6600 (c) 66
  20. 20.Best estimate of 2655 ÷ 28? (a) 890 (b) 89 (c) 8900
  21. 21.Best estimate of 4402 ÷ 51? (a) 8800 (b) 880 (c) 88
  22. 22.√40 to 1 decimal place? (a) 6.5 (b) 6.4 (c) 6.3 (d) 6.2
  23. 23.√30 to 1 decimal place? (a) 5.4 (b) 5.6 (c) 5.5 (d) 5.7
  24. 24.Best estimate of 2922 ÷ 34? (a) 9700 (b) 97 (c) 970
  25. 25.Best estimate of 978 ÷ 26? (a) 330 (b) 3300 (c) 33
  26. 26.Best estimate of 3395 ÷ 62? (a) 57 (b) 5700 (c) 570
  27. 27.Best estimate of 4847 ÷ 52? (a) 970 (b) 97 (c) 9700
  28. 28.√35 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 5.8 (d) 5.7
  29. 29.Best estimate of 2024 ÷ 82? (a) 2500 (b) 25 (c) 250
  30. 30.Best estimate of 5528 ÷ 76? (a) 69 (b) 690 (c) 6900
  31. 31.Best estimate of 629 ÷ 43? (a) 1600 (b) 16 (c) 160
  32. 32.Best estimate of 2458 ÷ 33? (a) 82 (b) 820 (c) 8200
  33. 33.Best estimate of 1507 ÷ 69? (a) 2200 (b) 220 (c) 22
  34. 34.Best estimate of 5043 ÷ 58? (a) 84 (b) 840 (c) 8400
  35. 35.√92 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.5 (d) 9.7
  36. 36.√34 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.8 (d) 5.9
  37. 37.Best estimate of 1746 ÷ 31? (a) 5800 (b) 580 (c) 58
  38. 38.√32 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.8 (d) 5.5
  39. 39.Best estimate of 1013 ÷ 83? (a) 13 (b) 130 (c) 1300
  40. 40.Best estimate of 2295 ÷ 84? (a) 2900 (b) 29 (c) 290

Answer key

  1. 31
  2. 6.2
  3. 35
  4. 9.3
  5. 6.4
  6. 24
  7. 9.9
  8. 93
  9. 26
  10. 80
  11. 93
  12. 19
  13. 7.1
  14. 42
  15. 8.3
  16. 6.7
  17. 7.9
  18. 50
  19. 66
  20. 89
  21. 88
  22. 6.3
  23. 5.5
  24. 97
  25. 33
  26. 57
  27. 97
  28. 5.9
  29. 25
  30. 69
  31. 16
  32. 82
  33. 22
  34. 84
  35. 9.6
  36. 5.8
  37. 58
  38. 5.7
  39. 13
  40. 29

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