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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 494 · 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 878 ÷ 26? (a) 2900 (b) 29 (c) 290
  2. 2.Best estimate of 1812 ÷ 44? (a) 4500 (b) 45 (c) 450
  3. 3.√65 to 1 decimal place? (a) 8.1 (b) 8.4 (c) 8.2 (d) 8.3
  4. 4.Best estimate of 2864 ÷ 48? (a) 57 (b) 5700 (c) 570
  5. 5.√32 to 1 decimal place? (a) 5.7 (b) 5.4 (c) 5.5 (d) 5.6
  6. 6.√37 to 1 decimal place? (a) 6.1 (b) 6.4 (c) 6.2 (d) 6.3
  7. 7.Best estimate of 2560 ÷ 63? (a) 4300 (b) 430 (c) 43
  8. 8.√83 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.0 (d) 9.1
  9. 9.√50 to 1 decimal place? (a) 7.0 (b) 6.9 (c) 6.8 (d) 7.1
  10. 10.√26 to 1 decimal place? (a) 5.1 (b) 5.0 (c) 4.9 (d) 5.2
  11. 11.Best estimate of 3934 ÷ 41? (a) 980 (b) 98 (c) 9800
  12. 12.√92 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.4 (d) 9.3
  13. 13.Best estimate of 3163 ÷ 46? (a) 630 (b) 6300 (c) 63
  14. 14.√94 to 1 decimal place? (a) 10.0 (b) 9.9 (c) 9.8 (d) 9.7
  15. 15.√20 to 1 decimal place? (a) 4.6 (b) 4.8 (c) 4.7 (d) 4.5
  16. 16.Best estimate of 8025 ÷ 87? (a) 8900 (b) 89 (c) 890
  17. 17.√76 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.4 (d) 8.5
  18. 18.Best estimate of 458 ÷ 21? (a) 230 (b) 23 (c) 2300
  19. 19.√72 to 1 decimal place? (a) 8.6 (b) 8.8 (c) 8.5 (d) 8.7
  20. 20.Best estimate of 574 ÷ 47? (a) 1100 (b) 110 (c) 11
  21. 21.Best estimate of 1510 ÷ 84? (a) 190 (b) 19 (c) 1900
  22. 22.√77 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.6 (d) 8.9
  23. 23.Best estimate of 6624 ÷ 76? (a) 830 (b) 8300 (c) 83
  24. 24.√61 to 1 decimal place? (a) 7.9 (b) 7.8 (c) 7.6 (d) 7.7
  25. 25.√34 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 5.7 (d) 5.8
  26. 26.Best estimate of 2099 ÷ 47? (a) 4200 (b) 420 (c) 42
  27. 27.Best estimate of 2036 ÷ 86? (a) 2300 (b) 23 (c) 230
  28. 28.Best estimate of 1107 ÷ 31? (a) 370 (b) 37 (c) 3700
  29. 29.Best estimate of 6226 ÷ 67? (a) 8900 (b) 890 (c) 89
  30. 30.Best estimate of 2850 ÷ 69? (a) 410 (b) 4100 (c) 41
  31. 31.Best estimate of 1477 ÷ 27? (a) 49 (b) 490 (c) 4900
  32. 32.Best estimate of 2326 ÷ 44? (a) 580 (b) 5800 (c) 58
  33. 33.Best estimate of 995 ÷ 66? (a) 140 (b) 1400 (c) 14
  34. 34.Best estimate of 1580 ÷ 31? (a) 53 (b) 5300 (c) 530
  35. 35.Best estimate of 2536 ÷ 87? (a) 280 (b) 28 (c) 2800
  36. 36.√23 to 1 decimal place? (a) 4.6 (b) 4.8 (c) 4.9 (d) 4.7
  37. 37.Best estimate of 1495 ÷ 22? (a) 7500 (b) 750 (c) 75
  38. 38.Best estimate of 948 ÷ 26? (a) 3200 (b) 320 (c) 32
  39. 39.Best estimate of 5093 ÷ 82? (a) 640 (b) 6400 (c) 64
  40. 40.Best estimate of 2844 ÷ 46? (a) 57 (b) 570 (c) 5700

Answer key

  1. 29
  2. 45
  3. 8.1
  4. 57
  5. 5.7
  6. 6.1
  7. 43
  8. 9.1
  9. 7.1
  10. 5.1
  11. 98
  12. 9.6
  13. 63
  14. 9.7
  15. 4.5
  16. 89
  17. 8.7
  18. 23
  19. 8.5
  20. 11
  21. 19
  22. 8.8
  23. 83
  24. 7.8
  25. 5.8
  26. 42
  27. 23
  28. 37
  29. 89
  30. 41
  31. 49
  32. 58
  33. 14
  34. 53
  35. 28
  36. 4.8
  37. 75
  38. 32
  39. 64
  40. 57

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