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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 681 · 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.√65 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 7.8 (d) 8.1
  2. 2.Best estimate of 7775 ÷ 84? (a) 970 (b) 97 (c) 9700
  3. 3.√48 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 6.7 (d) 7.0
  4. 4.Best estimate of 545 ÷ 21? (a) 2700 (b) 270 (c) 27
  5. 5.√74 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.8 (d) 8.5
  6. 6.Best estimate of 2790 ÷ 63? (a) 47 (b) 470 (c) 4700
  7. 7.√45 to 1 decimal place? (a) 6.8 (b) 6.6 (c) 6.7 (d) 6.5
  8. 8.√82 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.1 (d) 9.4
  9. 9.√69 to 1 decimal place? (a) 8.3 (b) 8.0 (c) 8.2 (d) 8.1
  10. 10.√98 to 1 decimal place? (a) 10.1 (b) 10.2 (c) 10.0 (d) 9.9
  11. 11.Best estimate of 4757 ÷ 66? (a) 6800 (b) 68 (c) 680
  12. 12.Best estimate of 882 ÷ 32? (a) 29 (b) 290 (c) 2900
  13. 13.√52 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 6.9 (d) 7.0
  14. 14.Best estimate of 2696 ÷ 69? (a) 3900 (b) 39 (c) 390
  15. 15.√75 to 1 decimal place? (a) 8.5 (b) 8.7 (c) 8.6 (d) 8.4
  16. 16.√86 to 1 decimal place? (a) 9.3 (b) 9.6 (c) 9.5 (d) 9.4
  17. 17.Best estimate of 3894 ÷ 66? (a) 5600 (b) 56 (c) 560
  18. 18.Best estimate of 1825 ÷ 38? (a) 460 (b) 46 (c) 4600
  19. 19.√44 to 1 decimal place? (a) 6.7 (b) 6.6 (c) 6.8 (d) 6.9
  20. 20.√59 to 1 decimal place? (a) 7.8 (b) 8.0 (c) 7.9 (d) 7.7
  21. 21.√78 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 8.9 (d) 8.8
  22. 22.Best estimate of 4309 ÷ 88? (a) 4800 (b) 48 (c) 480
  23. 23.Best estimate of 6068 ÷ 89? (a) 6700 (b) 67 (c) 670
  24. 24.Best estimate of 299 ÷ 23? (a) 150 (b) 1500 (c) 15
  25. 25.Best estimate of 3561 ÷ 79? (a) 450 (b) 45 (c) 4500
  26. 26.Best estimate of 3136 ÷ 88? (a) 350 (b) 35 (c) 3500
  27. 27.Best estimate of 920 ÷ 36? (a) 2300 (b) 230 (c) 23
  28. 28.√67 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.1 (d) 8.2
  29. 29.√84 to 1 decimal place? (a) 9.4 (b) 9.2 (c) 9.3 (d) 9.1
  30. 30.Best estimate of 2348 ÷ 38? (a) 5900 (b) 59 (c) 590
  31. 31.Best estimate of 3481 ÷ 43? (a) 870 (b) 87 (c) 8700
  32. 32.Best estimate of 997 ÷ 66? (a) 140 (b) 1400 (c) 14
  33. 33.√26 to 1 decimal place? (a) 5.2 (b) 5.4 (c) 5.1 (d) 5.3
  34. 34.√61 to 1 decimal place? (a) 7.6 (b) 7.9 (c) 7.7 (d) 7.8
  35. 35.Best estimate of 1247 ÷ 76? (a) 16 (b) 1600 (c) 160
  36. 36.Best estimate of 2512 ÷ 88? (a) 2800 (b) 28 (c) 280
  37. 37.Best estimate of 4089 ÷ 73? (a) 58 (b) 580 (c) 5800
  38. 38.Best estimate of 6114 ÷ 66? (a) 870 (b) 8700 (c) 87
  39. 39.Best estimate of 1281 ÷ 26? (a) 4300 (b) 430 (c) 43
  40. 40.Best estimate of 4072 ÷ 82? (a) 510 (b) 51 (c) 5100

Answer key

  1. 8.1
  2. 97
  3. 6.9
  4. 27
  5. 8.6
  6. 47
  7. 6.7
  8. 9.1
  9. 8.3
  10. 9.9
  11. 68
  12. 29
  13. 7.2
  14. 39
  15. 8.7
  16. 9.3
  17. 56
  18. 46
  19. 6.6
  20. 7.7
  21. 8.8
  22. 48
  23. 67
  24. 15
  25. 45
  26. 35
  27. 23
  28. 8.2
  29. 9.2
  30. 59
  31. 87
  32. 14
  33. 5.1
  34. 7.8
  35. 16
  36. 28
  37. 58
  38. 87
  39. 43
  40. 51

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