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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 677 · 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 3665 ÷ 44? (a) 92 (b) 920 (c) 9200
  2. 2.√44 to 1 decimal place? (a) 6.9 (b) 6.7 (c) 6.8 (d) 6.6
  3. 3.√67 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 8.2 (d) 7.9
  4. 4.√29 to 1 decimal place? (a) 5.5 (b) 5.7 (c) 5.4 (d) 5.6
  5. 5.Best estimate of 1484 ÷ 26? (a) 4900 (b) 49 (c) 490
  6. 6.√92 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.6 (d) 9.8
  7. 7.Best estimate of 4596 ÷ 83? (a) 570 (b) 57 (c) 5700
  8. 8.√69 to 1 decimal place? (a) 8.3 (b) 8.5 (c) 8.6 (d) 8.4
  9. 9.Best estimate of 480 ÷ 22? (a) 240 (b) 2400 (c) 24
  10. 10.Best estimate of 4206 ÷ 51? (a) 84 (b) 8400 (c) 840
  11. 11.Best estimate of 1242 ÷ 22? (a) 6200 (b) 62 (c) 620
  12. 12.Best estimate of 280 ÷ 21? (a) 140 (b) 1400 (c) 14
  13. 13.Best estimate of 7054 ÷ 76? (a) 88 (b) 8800 (c) 880
  14. 14.Best estimate of 6876 ÷ 83? (a) 8600 (b) 86 (c) 860
  15. 15.Best estimate of 5673 ÷ 82? (a) 7100 (b) 71 (c) 710
  16. 16.Best estimate of 720 ÷ 21? (a) 3600 (b) 360 (c) 36
  17. 17.√22 to 1 decimal place? (a) 4.7 (b) 4.8 (c) 4.9 (d) 5.0
  18. 18.√82 to 1 decimal place? (a) 9.1 (b) 9.4 (c) 9.2 (d) 9.3
  19. 19.Best estimate of 1634 ÷ 37? (a) 410 (b) 4100 (c) 41
  20. 20.√75 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.5 (d) 8.6
  21. 21.Best estimate of 2620 ÷ 68? (a) 370 (b) 3700 (c) 37
  22. 22.Best estimate of 1825 ÷ 24? (a) 9100 (b) 91 (c) 910
  23. 23.Best estimate of 3336 ÷ 86? (a) 37 (b) 3700 (c) 370
  24. 24.√55 to 1 decimal place? (a) 7.5 (b) 7.2 (c) 7.3 (d) 7.4
  25. 25.Best estimate of 1082 ÷ 57? (a) 180 (b) 18 (c) 1800
  26. 26.Best estimate of 2192 ÷ 84? (a) 2700 (b) 27 (c) 270
  27. 27.√24 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.8 (d) 4.9
  28. 28.Best estimate of 1726 ÷ 52? (a) 350 (b) 3500 (c) 35
  29. 29.Best estimate of 5100 ÷ 88? (a) 57 (b) 5700 (c) 570
  30. 30.Best estimate of 2222 ÷ 27? (a) 740 (b) 74 (c) 7400
  31. 31.Best estimate of 1079 ÷ 29? (a) 360 (b) 3600 (c) 36
  32. 32.√96 to 1 decimal place? (a) 9.8 (b) 10.0 (c) 9.9 (d) 10.1
  33. 33.√84 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.2 (d) 9.1
  34. 34.√40 to 1 decimal place? (a) 6.2 (b) 6.4 (c) 6.3 (d) 6.5
  35. 35.Best estimate of 4253 ÷ 57? (a) 7100 (b) 71 (c) 710
  36. 36.Best estimate of 1814 ÷ 61? (a) 30 (b) 300 (c) 3000
  37. 37.√94 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.5 (d) 9.4
  38. 38.Best estimate of 4671 ÷ 51? (a) 93 (b) 930 (c) 9300
  39. 39.Best estimate of 651 ÷ 38? (a) 160 (b) 16 (c) 1600
  40. 40.Best estimate of 4369 ÷ 76? (a) 5500 (b) 550 (c) 55

Answer key

  1. 92
  2. 6.6
  3. 8.2
  4. 5.4
  5. 49
  6. 9.6
  7. 57
  8. 8.3
  9. 24
  10. 84
  11. 62
  12. 14
  13. 88
  14. 86
  15. 71
  16. 36
  17. 4.7
  18. 9.1
  19. 41
  20. 8.7
  21. 37
  22. 91
  23. 37
  24. 7.4
  25. 18
  26. 27
  27. 4.9
  28. 35
  29. 57
  30. 74
  31. 36
  32. 9.8
  33. 9.2
  34. 6.3
  35. 71
  36. 30
  37. 9.7
  38. 93
  39. 16
  40. 55

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