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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 425 · 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.√51 to 1 decimal place? (a) 6.9 (b) 7.1 (c) 7.0 (d) 6.8
  2. 2.Best estimate of 4495 ÷ 86? (a) 500 (b) 5000 (c) 50
  3. 3.Best estimate of 4073 ÷ 54? (a) 810 (b) 81 (c) 8100
  4. 4.Best estimate of 5035 ÷ 58? (a) 8400 (b) 840 (c) 84
  5. 5.√40 to 1 decimal place? (a) 6.6 (b) 6.5 (c) 6.4 (d) 6.3
  6. 6.Best estimate of 2103 ÷ 56? (a) 350 (b) 3500 (c) 35
  7. 7.Best estimate of 3375 ÷ 49? (a) 6800 (b) 68 (c) 680
  8. 8.Best estimate of 3816 ÷ 44? (a) 95 (b) 950 (c) 9500
  9. 9.Best estimate of 649 ÷ 54? (a) 130 (b) 13 (c) 1300
  10. 10.Best estimate of 3513 ÷ 54? (a) 70 (b) 7000 (c) 700
  11. 11.Best estimate of 2778 ÷ 46? (a) 5600 (b) 560 (c) 56
  12. 12.Best estimate of 1786 ÷ 39? (a) 45 (b) 450 (c) 4500
  13. 13.Best estimate of 4874 ÷ 81? (a) 6100 (b) 610 (c) 61
  14. 14.Best estimate of 1340 ÷ 38? (a) 340 (b) 3400 (c) 34
  15. 15.Best estimate of 1169 ÷ 26? (a) 3900 (b) 390 (c) 39
  16. 16.√96 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 10.1 (d) 10.0
  17. 17.√65 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 7.9 (d) 7.8
  18. 18.√83 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 8.9 (d) 8.8
  19. 19.√34 to 1 decimal place? (a) 5.9 (b) 6.1 (c) 6.0 (d) 5.8
  20. 20.√53 to 1 decimal place? (a) 7.1 (b) 7.4 (c) 7.2 (d) 7.3
  21. 21.√98 to 1 decimal place? (a) 9.8 (b) 9.6 (c) 9.7 (d) 9.9
  22. 22.√37 to 1 decimal place? (a) 6.2 (b) 6.0 (c) 6.1 (d) 6.3
  23. 23.Best estimate of 1202 ÷ 33? (a) 4000 (b) 40 (c) 400
  24. 24.Best estimate of 2676 ÷ 62? (a) 4500 (b) 45 (c) 450
  25. 25.√85 to 1 decimal place? (a) 9.2 (b) 9.0 (c) 9.3 (d) 9.1
  26. 26.√82 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.0 (d) 8.9
  27. 27.Best estimate of 403 ÷ 32? (a) 13 (b) 130 (c) 1300
  28. 28.√48 to 1 decimal place? (a) 7.0 (b) 6.9 (c) 6.8 (d) 6.7
  29. 29.Best estimate of 3437 ÷ 43? (a) 8600 (b) 860 (c) 86
  30. 30.√77 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.9 (d) 9.0
  31. 31.Best estimate of 3654 ÷ 58? (a) 61 (b) 610 (c) 6100
  32. 32.Best estimate of 1136 ÷ 42? (a) 2800 (b) 28 (c) 280
  33. 33.Best estimate of 1302 ÷ 36? (a) 330 (b) 33 (c) 3300
  34. 34.Best estimate of 689 ÷ 32? (a) 2300 (b) 230 (c) 23
  35. 35.Best estimate of 2412 ÷ 28? (a) 8000 (b) 800 (c) 80
  36. 36.√44 to 1 decimal place? (a) 6.4 (b) 6.7 (c) 6.6 (d) 6.5
  37. 37.Best estimate of 2129 ÷ 26? (a) 7100 (b) 71 (c) 710
  38. 38.√90 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.8 (d) 9.7
  39. 39.Best estimate of 5358 ÷ 82? (a) 67 (b) 670 (c) 6700
  40. 40.Best estimate of 1737 ÷ 63? (a) 290 (b) 2900 (c) 29

Answer key

  1. 7.1
  2. 50
  3. 81
  4. 84
  5. 6.3
  6. 35
  7. 68
  8. 95
  9. 13
  10. 70
  11. 56
  12. 45
  13. 61
  14. 34
  15. 39
  16. 9.8
  17. 8.1
  18. 9.1
  19. 5.8
  20. 7.3
  21. 9.9
  22. 6.1
  23. 40
  24. 45
  25. 9.2
  26. 9.1
  27. 13
  28. 6.9
  29. 86
  30. 8.8
  31. 61
  32. 28
  33. 33
  34. 23
  35. 80
  36. 6.6
  37. 71
  38. 9.5
  39. 67
  40. 29

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