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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 596 · 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 3174 ÷ 83? (a) 4000 (b) 40 (c) 400
  2. 2.√61 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 7.9 (d) 7.8
  3. 3.√79 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 9.1 (d) 8.8
  4. 4.Best estimate of 2602 ÷ 46? (a) 520 (b) 5200 (c) 52
  5. 5.Best estimate of 5114 ÷ 63? (a) 85 (b) 8500 (c) 850
  6. 6.Best estimate of 7378 ÷ 81? (a) 920 (b) 9200 (c) 92
  7. 7.√67 to 1 decimal place? (a) 8.2 (b) 8.5 (c) 8.4 (d) 8.3
  8. 8.Best estimate of 5794 ÷ 62? (a) 970 (b) 97 (c) 9700
  9. 9.√45 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 6.7 (d) 7.0
  10. 10.√23 to 1 decimal place? (a) 4.7 (b) 4.6 (c) 4.8 (d) 4.9
  11. 11.√50 to 1 decimal place? (a) 6.8 (b) 7.1 (c) 7.0 (d) 6.9
  12. 12.Best estimate of 1244 ÷ 89? (a) 14 (b) 140 (c) 1400
  13. 13.Best estimate of 3189 ÷ 43? (a) 800 (b) 80 (c) 8000
  14. 14.Best estimate of 1523 ÷ 37? (a) 3800 (b) 380 (c) 38
  15. 15.Best estimate of 5151 ÷ 82? (a) 6400 (b) 64 (c) 640
  16. 16.Best estimate of 1634 ÷ 29? (a) 540 (b) 54 (c) 5400
  17. 17.Best estimate of 1276 ÷ 38? (a) 3200 (b) 32 (c) 320
  18. 18.Best estimate of 2536 ÷ 32? (a) 850 (b) 8500 (c) 85
  19. 19.√28 to 1 decimal place? (a) 5.5 (b) 5.3 (c) 5.4 (d) 5.6
  20. 20.Best estimate of 6088 ÷ 72? (a) 8700 (b) 87 (c) 870
  21. 21.√27 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.5 (d) 5.4
  22. 22.Best estimate of 4063 ÷ 69? (a) 580 (b) 58 (c) 5800
  23. 23.Best estimate of 406 ÷ 33? (a) 1400 (b) 14 (c) 140
  24. 24.Best estimate of 7694 ÷ 82? (a) 9600 (b) 960 (c) 96
  25. 25.√26 to 1 decimal place? (a) 5.2 (b) 5.1 (c) 5.3 (d) 5.4
  26. 26.√89 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.4 (d) 9.5
  27. 27.√98 to 1 decimal place? (a) 10.0 (b) 9.8 (c) 9.9 (d) 10.1
  28. 28.Best estimate of 2734 ÷ 89? (a) 300 (b) 3000 (c) 30
  29. 29.Best estimate of 583 ÷ 26? (a) 19 (b) 1900 (c) 190
  30. 30.√43 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 6.6 (d) 6.9
  31. 31.√58 to 1 decimal place? (a) 7.4 (b) 7.6 (c) 7.7 (d) 7.5
  32. 32.Best estimate of 6903 ÷ 73? (a) 99 (b) 9900 (c) 990
  33. 33.√55 to 1 decimal place? (a) 7.4 (b) 7.2 (c) 7.3 (d) 7.1
  34. 34.Best estimate of 2408 ÷ 53? (a) 480 (b) 48 (c) 4800
  35. 35.Best estimate of 5666 ÷ 71? (a) 8100 (b) 810 (c) 81
  36. 36.Best estimate of 454 ÷ 37? (a) 1100 (b) 110 (c) 11
  37. 37.Best estimate of 5701 ÷ 69? (a) 81 (b) 8100 (c) 810
  38. 38.Best estimate of 2877 ÷ 58? (a) 480 (b) 48 (c) 4800
  39. 39.√62 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 7.6 (d) 7.9
  40. 40.Best estimate of 1655 ÷ 39? (a) 410 (b) 4100 (c) 41

Answer key

  1. 40
  2. 7.8
  3. 8.9
  4. 52
  5. 85
  6. 92
  7. 8.2
  8. 97
  9. 6.7
  10. 4.8
  11. 7.1
  12. 14
  13. 80
  14. 38
  15. 64
  16. 54
  17. 32
  18. 85
  19. 5.3
  20. 87
  21. 5.2
  22. 58
  23. 14
  24. 96
  25. 5.1
  26. 9.4
  27. 9.9
  28. 30
  29. 19
  30. 6.6
  31. 7.6
  32. 99
  33. 7.4
  34. 48
  35. 81
  36. 11
  37. 81
  38. 48
  39. 7.9
  40. 41

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