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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 502 · 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 2246 ÷ 26? (a) 750 (b) 7500 (c) 75
  2. 2.√26 to 1 decimal place? (a) 5.3 (b) 5.1 (c) 5.0 (d) 5.2
  3. 3.Best estimate of 483 ÷ 31? (a) 16 (b) 160 (c) 1600
  4. 4.Best estimate of 1253 ÷ 72? (a) 1800 (b) 18 (c) 180
  5. 5.√89 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.7 (d) 9.5
  6. 6.√67 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.5 (d) 8.2
  7. 7.Best estimate of 2200 ÷ 53? (a) 4400 (b) 440 (c) 44
  8. 8.Best estimate of 1118 ÷ 52? (a) 2200 (b) 22 (c) 220
  9. 9.√80 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 9.1 (d) 9.0
  10. 10.Best estimate of 5339 ÷ 76? (a) 670 (b) 6700 (c) 67
  11. 11.Best estimate of 3017 ÷ 87? (a) 3400 (b) 34 (c) 340
  12. 12.Best estimate of 1640 ÷ 82? (a) 210 (b) 21 (c) 2100
  13. 13.Best estimate of 3199 ÷ 66? (a) 460 (b) 4600 (c) 46
  14. 14.√43 to 1 decimal place? (a) 6.8 (b) 6.6 (c) 6.9 (d) 6.7
  15. 15.Best estimate of 5598 ÷ 82? (a) 70 (b) 7000 (c) 700
  16. 16.Best estimate of 2506 ÷ 72? (a) 360 (b) 3600 (c) 36
  17. 17.√30 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.5 (d) 5.2
  18. 18.Best estimate of 3820 ÷ 67? (a) 55 (b) 5500 (c) 550
  19. 19.√61 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 8.0 (d) 8.1
  20. 20.Best estimate of 824 ÷ 26? (a) 2700 (b) 27 (c) 270
  21. 21.Best estimate of 1786 ÷ 38? (a) 4500 (b) 45 (c) 450
  22. 22.Best estimate of 1114 ÷ 33? (a) 3700 (b) 37 (c) 370
  23. 23.√92 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.5 (d) 9.4
  24. 24.√96 to 1 decimal place? (a) 9.9 (b) 9.7 (c) 10.0 (d) 9.8
  25. 25.Best estimate of 3460 ÷ 39? (a) 8700 (b) 87 (c) 870
  26. 26.√94 to 1 decimal place? (a) 10.0 (b) 9.7 (c) 9.8 (d) 9.9
  27. 27.Best estimate of 1645 ÷ 22? (a) 820 (b) 82 (c) 8200
  28. 28.Best estimate of 1201 ÷ 87? (a) 13 (b) 1300 (c) 130
  29. 29.Best estimate of 4511 ÷ 62? (a) 7500 (b) 750 (c) 75
  30. 30.√34 to 1 decimal place? (a) 5.8 (b) 5.6 (c) 5.5 (d) 5.7
  31. 31.Best estimate of 2260 ÷ 52? (a) 450 (b) 4500 (c) 45
  32. 32.Best estimate of 1368 ÷ 67? (a) 2000 (b) 200 (c) 20
  33. 33.√27 to 1 decimal place? (a) 5.2 (b) 5.0 (c) 5.1 (d) 4.9
  34. 34.√47 to 1 decimal place? (a) 6.9 (b) 6.7 (c) 6.6 (d) 6.8
  35. 35.Best estimate of 7180 ÷ 82? (a) 90 (b) 900 (c) 9000
  36. 36.Best estimate of 1985 ÷ 38? (a) 500 (b) 50 (c) 5000
  37. 37.√87 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.5 (d) 9.3
  38. 38.Best estimate of 3625 ÷ 43? (a) 9100 (b) 910 (c) 91
  39. 39.Best estimate of 2978 ÷ 36? (a) 740 (b) 7400 (c) 74
  40. 40.√22 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 5.0 (d) 4.9

Answer key

  1. 75
  2. 5.1
  3. 16
  4. 18
  5. 9.4
  6. 8.2
  7. 44
  8. 22
  9. 8.9
  10. 67
  11. 34
  12. 21
  13. 46
  14. 6.6
  15. 70
  16. 36
  17. 5.5
  18. 55
  19. 7.8
  20. 27
  21. 45
  22. 37
  23. 9.6
  24. 9.8
  25. 87
  26. 9.7
  27. 82
  28. 13
  29. 75
  30. 5.8
  31. 45
  32. 20
  33. 5.2
  34. 6.9
  35. 90
  36. 50
  37. 9.3
  38. 91
  39. 74
  40. 4.7

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