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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 875 · 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.√74 to 1 decimal place? (a) 8.5 (b) 8.4 (c) 8.6 (d) 8.3
  2. 2.Best estimate of 5883 ÷ 89? (a) 6500 (b) 650 (c) 65
  3. 3.√51 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.4 (d) 7.1
  4. 4.Best estimate of 2669 ÷ 54? (a) 530 (b) 53 (c) 5300
  5. 5.√41 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.3 (d) 6.4
  6. 6.Best estimate of 3424 ÷ 86? (a) 380 (b) 3800 (c) 38
  7. 7.Best estimate of 412 ÷ 21? (a) 2100 (b) 21 (c) 210
  8. 8.Best estimate of 1230 ÷ 43? (a) 3100 (b) 310 (c) 31
  9. 9.Best estimate of 983 ÷ 28? (a) 330 (b) 3300 (c) 33
  10. 10.Best estimate of 3256 ÷ 63? (a) 540 (b) 5400 (c) 54
  11. 11.√87 to 1 decimal place? (a) 9.1 (b) 9.3 (c) 9.2 (d) 9.0
  12. 12.√84 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 9.1 (d) 9.2
  13. 13.√53 to 1 decimal place? (a) 7.5 (b) 7.3 (c) 7.6 (d) 7.4
  14. 14.√89 to 1 decimal place? (a) 9.7 (b) 9.4 (c) 9.5 (d) 9.6
  15. 15.√42 to 1 decimal place? (a) 6.5 (b) 6.3 (c) 6.6 (d) 6.4
  16. 16.√37 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 6.0 (d) 6.3
  17. 17.Best estimate of 4021 ÷ 58? (a) 67 (b) 670 (c) 6700
  18. 18.Best estimate of 7201 ÷ 76? (a) 9000 (b) 900 (c) 90
  19. 19.Best estimate of 3205 ÷ 89? (a) 36 (b) 3600 (c) 360
  20. 20.Best estimate of 1850 ÷ 79? (a) 230 (b) 2300 (c) 23
  21. 21.Best estimate of 729 ÷ 22? (a) 360 (b) 3600 (c) 36
  22. 22.Best estimate of 1483 ÷ 53? (a) 300 (b) 3000 (c) 30
  23. 23.Best estimate of 2483 ÷ 28? (a) 8300 (b) 830 (c) 83
  24. 24.√23 to 1 decimal place? (a) 4.7 (b) 4.8 (c) 4.9 (d) 4.6
  25. 25.Best estimate of 3029 ÷ 32? (a) 101 (b) 1010 (c) 10100
  26. 26.√20 to 1 decimal place? (a) 4.3 (b) 4.4 (c) 4.5 (d) 4.2
  27. 27.Best estimate of 4490 ÷ 57? (a) 7500 (b) 75 (c) 750
  28. 28.√82 to 1 decimal place? (a) 8.9 (b) 9.1 (c) 9.2 (d) 9.0
  29. 29.Best estimate of 2473 ÷ 66? (a) 350 (b) 3500 (c) 35
  30. 30.Best estimate of 6191 ÷ 74? (a) 88 (b) 880 (c) 8800
  31. 31.Best estimate of 3010 ÷ 81? (a) 3800 (b) 380 (c) 38
  32. 32.Best estimate of 1429 ÷ 76? (a) 180 (b) 1800 (c) 18
  33. 33.√63 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 7.9 (d) 8.0
  34. 34.Best estimate of 3533 ÷ 69? (a) 500 (b) 5000 (c) 50
  35. 35.Best estimate of 1105 ÷ 23? (a) 55 (b) 550 (c) 5500
  36. 36.√92 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.7 (d) 9.5
  37. 37.√66 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.1 (d) 8.2
  38. 38.√47 to 1 decimal place? (a) 6.6 (b) 6.8 (c) 6.9 (d) 6.7
  39. 39.Best estimate of 2316 ÷ 36? (a) 580 (b) 58 (c) 5800
  40. 40.Best estimate of 6478 ÷ 86? (a) 72 (b) 7200 (c) 720

Answer key

  1. 8.6
  2. 65
  3. 7.1
  4. 53
  5. 6.4
  6. 38
  7. 21
  8. 31
  9. 33
  10. 54
  11. 9.3
  12. 9.2
  13. 7.3
  14. 9.4
  15. 6.5
  16. 6.1
  17. 67
  18. 90
  19. 36
  20. 23
  21. 36
  22. 30
  23. 83
  24. 4.8
  25. 101
  26. 4.5
  27. 75
  28. 9.1
  29. 35
  30. 88
  31. 38
  32. 18
  33. 7.9
  34. 50
  35. 55
  36. 9.6
  37. 8.1
  38. 6.9
  39. 58
  40. 72

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