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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 415 · 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 1854 ÷ 31? (a) 620 (b) 6200 (c) 62
  2. 2.Best estimate of 4480 ÷ 79? (a) 56 (b) 560 (c) 5600
  3. 3.√87 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.5 (d) 9.6
  4. 4.√29 to 1 decimal place? (a) 5.2 (b) 5.1 (c) 5.3 (d) 5.4
  5. 5.Best estimate of 746 ÷ 26? (a) 250 (b) 2500 (c) 25
  6. 6.Best estimate of 2090 ÷ 43? (a) 5200 (b) 520 (c) 52
  7. 7.Best estimate of 4425 ÷ 86? (a) 4900 (b) 490 (c) 49
  8. 8.Best estimate of 5422 ÷ 62? (a) 900 (b) 9000 (c) 90
  9. 9.Best estimate of 4128 ÷ 56? (a) 69 (b) 690 (c) 6900
  10. 10.√27 to 1 decimal place? (a) 5.1 (b) 5.2 (c) 5.3 (d) 5.0
  11. 11.√40 to 1 decimal place? (a) 6.5 (b) 6.4 (c) 6.6 (d) 6.3
  12. 12.Best estimate of 3266 ÷ 48? (a) 650 (b) 6500 (c) 65
  13. 13.Best estimate of 618 ÷ 29? (a) 210 (b) 2100 (c) 21
  14. 14.Best estimate of 1177 ÷ 59? (a) 2000 (b) 20 (c) 200
  15. 15.√34 to 1 decimal place? (a) 5.8 (b) 5.6 (c) 5.7 (d) 5.5
  16. 16.√82 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 9.1 (d) 9.2
  17. 17.Best estimate of 2676 ÷ 89? (a) 300 (b) 3000 (c) 30
  18. 18.Best estimate of 7916 ÷ 86? (a) 88 (b) 8800 (c) 880
  19. 19.Best estimate of 4003 ÷ 82? (a) 5000 (b) 50 (c) 500
  20. 20.√23 to 1 decimal place? (a) 4.7 (b) 4.6 (c) 4.8 (d) 4.9
  21. 21.Best estimate of 1309 ÷ 32? (a) 44 (b) 440 (c) 4400
  22. 22.√89 to 1 decimal place? (a) 9.7 (b) 9.5 (c) 9.6 (d) 9.4
  23. 23.Best estimate of 7120 ÷ 82? (a) 8900 (b) 890 (c) 89
  24. 24.Best estimate of 446 ÷ 31? (a) 1500 (b) 150 (c) 15
  25. 25.Best estimate of 2057 ÷ 71? (a) 2900 (b) 290 (c) 29
  26. 26.Best estimate of 469 ÷ 26? (a) 1600 (b) 16 (c) 160
  27. 27.Best estimate of 2807 ÷ 51? (a) 56 (b) 560 (c) 5600
  28. 28.Best estimate of 1486 ÷ 28? (a) 50 (b) 5000 (c) 500
  29. 29.Best estimate of 1210 ÷ 56? (a) 2000 (b) 20 (c) 200
  30. 30.Best estimate of 6674 ÷ 77? (a) 830 (b) 8300 (c) 83
  31. 31.Best estimate of 3072 ÷ 42? (a) 7700 (b) 770 (c) 77
  32. 32.√46 to 1 decimal place? (a) 6.6 (b) 6.8 (c) 6.7 (d) 6.9
  33. 33.Best estimate of 2780 ÷ 29? (a) 930 (b) 9300 (c) 93
  34. 34.√83 to 1 decimal place? (a) 9.3 (b) 9.1 (c) 9.0 (d) 9.2
  35. 35.√28 to 1 decimal place? (a) 5.1 (b) 5.2 (c) 5.4 (d) 5.3
  36. 36.Best estimate of 3936 ÷ 49? (a) 790 (b) 7900 (c) 79
  37. 37.√50 to 1 decimal place? (a) 7.2 (b) 7.0 (c) 7.1 (d) 6.9
  38. 38.√98 to 1 decimal place? (a) 10.1 (b) 10.0 (c) 10.2 (d) 9.9
  39. 39.Best estimate of 1330 ÷ 33? (a) 440 (b) 44 (c) 4400
  40. 40.Best estimate of 1288 ÷ 29? (a) 430 (b) 43 (c) 4300

Answer key

  1. 62
  2. 56
  3. 9.3
  4. 5.4
  5. 25
  6. 52
  7. 49
  8. 90
  9. 69
  10. 5.2
  11. 6.3
  12. 65
  13. 21
  14. 20
  15. 5.8
  16. 9.1
  17. 30
  18. 88
  19. 50
  20. 4.8
  21. 44
  22. 9.4
  23. 89
  24. 15
  25. 29
  26. 16
  27. 56
  28. 50
  29. 20
  30. 83
  31. 77
  32. 6.8
  33. 93
  34. 9.1
  35. 5.3
  36. 79
  37. 7.1
  38. 9.9
  39. 44
  40. 43

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