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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 765 · 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.√69 to 1 decimal place? (a) 8.5 (b) 8.4 (c) 8.2 (d) 8.3
  2. 2.Best estimate of 719 ÷ 47? (a) 14 (b) 1400 (c) 140
  3. 3.Best estimate of 1374 ÷ 52? (a) 270 (b) 27 (c) 2700
  4. 4.√32 to 1 decimal place? (a) 5.9 (b) 5.7 (c) 5.6 (d) 5.8
  5. 5.Best estimate of 1653 ÷ 42? (a) 410 (b) 41 (c) 4100
  6. 6.Best estimate of 1207 ÷ 61? (a) 200 (b) 20 (c) 2000
  7. 7.√27 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.4 (d) 5.1
  8. 8.√42 to 1 decimal place? (a) 6.5 (b) 6.7 (c) 6.8 (d) 6.6
  9. 9.Best estimate of 1693 ÷ 66? (a) 24 (b) 2400 (c) 240
  10. 10.Best estimate of 1385 ÷ 22? (a) 69 (b) 690 (c) 6900
  11. 11.Best estimate of 2120 ÷ 46? (a) 420 (b) 42 (c) 4200
  12. 12.√44 to 1 decimal place? (a) 6.7 (b) 6.9 (c) 6.6 (d) 6.8
  13. 13.√55 to 1 decimal place? (a) 7.3 (b) 7.2 (c) 7.4 (d) 7.5
  14. 14.√92 to 1 decimal place? (a) 9.9 (b) 9.6 (c) 9.7 (d) 9.8
  15. 15.Best estimate of 687 ÷ 43? (a) 1700 (b) 170 (c) 17
  16. 16.Best estimate of 2706 ÷ 54? (a) 54 (b) 540 (c) 5400
  17. 17.Best estimate of 1096 ÷ 42? (a) 270 (b) 2700 (c) 27
  18. 18.Best estimate of 1088 ÷ 38? (a) 270 (b) 2700 (c) 27
  19. 19.Best estimate of 2016 ÷ 86? (a) 220 (b) 22 (c) 2200
  20. 20.√28 to 1 decimal place? (a) 5.3 (b) 5.5 (c) 5.6 (d) 5.4
  21. 21.Best estimate of 2412 ÷ 46? (a) 48 (b) 480 (c) 4800
  22. 22.Best estimate of 3273 ÷ 42? (a) 82 (b) 8200 (c) 820
  23. 23.Best estimate of 3692 ÷ 72? (a) 5300 (b) 53 (c) 530
  24. 24.Best estimate of 5635 ÷ 66? (a) 810 (b) 81 (c) 8100
  25. 25.√26 to 1 decimal place? (a) 5.4 (b) 5.1 (c) 5.2 (d) 5.3
  26. 26.Best estimate of 7224 ÷ 82? (a) 900 (b) 9000 (c) 90
  27. 27.√52 to 1 decimal place? (a) 7.0 (b) 7.1 (c) 7.2 (d) 6.9
  28. 28.√23 to 1 decimal place? (a) 4.7 (b) 4.6 (c) 4.5 (d) 4.8
  29. 29.Best estimate of 4366 ÷ 86? (a) 49 (b) 4900 (c) 490
  30. 30.√79 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 8.8 (d) 8.7
  31. 31.Best estimate of 3663 ÷ 39? (a) 92 (b) 9200 (c) 920
  32. 32.√96 to 1 decimal place? (a) 10.0 (b) 9.7 (c) 9.9 (d) 9.8
  33. 33.Best estimate of 1498 ÷ 27? (a) 500 (b) 50 (c) 5000
  34. 34.√34 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 6.1 (d) 5.8
  35. 35.√24 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 5.1 (d) 4.8
  36. 36.Best estimate of 3047 ÷ 42? (a) 76 (b) 7600 (c) 760
  37. 37.√41 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.1 (d) 6.2
  38. 38.Best estimate of 3876 ÷ 66? (a) 550 (b) 5500 (c) 55
  39. 39.Best estimate of 916 ÷ 26? (a) 3100 (b) 31 (c) 310
  40. 40.Best estimate of 5439 ÷ 68? (a) 780 (b) 78 (c) 7800

Answer key

  1. 8.3
  2. 14
  3. 27
  4. 5.7
  5. 41
  6. 20
  7. 5.2
  8. 6.5
  9. 24
  10. 69
  11. 42
  12. 6.6
  13. 7.4
  14. 9.6
  15. 17
  16. 54
  17. 27
  18. 27
  19. 22
  20. 5.3
  21. 48
  22. 82
  23. 53
  24. 81
  25. 5.1
  26. 90
  27. 7.2
  28. 4.8
  29. 49
  30. 8.9
  31. 92
  32. 9.8
  33. 50
  34. 5.8
  35. 4.9
  36. 76
  37. 6.4
  38. 55
  39. 31
  40. 78

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