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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 890 · 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.√28 to 1 decimal place? (a) 5.1 (b) 5.3 (c) 5.0 (d) 5.2
  2. 2.Best estimate of 3118 ÷ 46? (a) 6200 (b) 62 (c) 620
  3. 3.Best estimate of 2506 ÷ 28? (a) 8400 (b) 84 (c) 840
  4. 4.Best estimate of 7799 ÷ 88? (a) 8700 (b) 87 (c) 870
  5. 5.√62 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 7.7 (d) 7.8
  6. 6.√32 to 1 decimal place? (a) 5.8 (b) 5.7 (c) 6.0 (d) 5.9
  7. 7.Best estimate of 1910 ÷ 56? (a) 32 (b) 3200 (c) 320
  8. 8.Best estimate of 6488 ÷ 76? (a) 81 (b) 810 (c) 8100
  9. 9.√67 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.2 (d) 8.1
  10. 10.Best estimate of 5902 ÷ 71? (a) 8400 (b) 84 (c) 840
  11. 11.Best estimate of 1257 ÷ 59? (a) 21 (b) 2100 (c) 210
  12. 12.Best estimate of 977 ÷ 62? (a) 1600 (b) 16 (c) 160
  13. 13.√21 to 1 decimal place? (a) 4.8 (b) 4.9 (c) 4.7 (d) 4.6
  14. 14.Best estimate of 2173 ÷ 64? (a) 36 (b) 3600 (c) 360
  15. 15.Best estimate of 602 ÷ 23? (a) 300 (b) 30 (c) 3000
  16. 16.Best estimate of 1155 ÷ 38? (a) 290 (b) 29 (c) 2900
  17. 17.Best estimate of 7072 ÷ 86? (a) 79 (b) 790 (c) 7900
  18. 18.√47 to 1 decimal place? (a) 7.0 (b) 6.9 (c) 6.8 (d) 6.7
  19. 19.Best estimate of 3513 ÷ 76? (a) 4400 (b) 44 (c) 440
  20. 20.√40 to 1 decimal place? (a) 6.3 (b) 6.0 (c) 6.1 (d) 6.2
  21. 21.Best estimate of 2849 ÷ 71? (a) 41 (b) 410 (c) 4100
  22. 22.Best estimate of 1547 ÷ 26? (a) 520 (b) 5200 (c) 52
  23. 23.√84 to 1 decimal place? (a) 9.1 (b) 9.3 (c) 9.4 (d) 9.2
  24. 24.Best estimate of 1055 ÷ 39? (a) 260 (b) 2600 (c) 26
  25. 25.Best estimate of 4955 ÷ 69? (a) 7100 (b) 71 (c) 710
  26. 26.Best estimate of 3013 ÷ 53? (a) 600 (b) 60 (c) 6000
  27. 27.√52 to 1 decimal place? (a) 7.1 (b) 6.9 (c) 7.2 (d) 7.0
  28. 28.√35 to 1 decimal place? (a) 5.7 (b) 5.9 (c) 5.6 (d) 5.8
  29. 29.Best estimate of 2205 ÷ 31? (a) 7400 (b) 74 (c) 740
  30. 30.√63 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 7.7 (d) 8.0
  31. 31.Best estimate of 1586 ÷ 21? (a) 790 (b) 7900 (c) 79
  32. 32.√94 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.9 (d) 9.8
  33. 33.Best estimate of 1611 ÷ 31? (a) 54 (b) 5400 (c) 540
  34. 34.Best estimate of 4587 ÷ 69? (a) 660 (b) 66 (c) 6600
  35. 35.√89 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.4 (d) 9.1
  36. 36.√76 to 1 decimal place? (a) 8.5 (b) 8.7 (c) 8.6 (d) 8.8
  37. 37.Best estimate of 855 ÷ 63? (a) 14 (b) 140 (c) 1400
  38. 38.Best estimate of 1468 ÷ 78? (a) 180 (b) 1800 (c) 18
  39. 39.√80 to 1 decimal place? (a) 9.1 (b) 8.8 (c) 9.0 (d) 8.9
  40. 40.Best estimate of 1951 ÷ 38? (a) 4900 (b) 49 (c) 490

Answer key

  1. 5.3
  2. 62
  3. 84
  4. 87
  5. 7.9
  6. 5.7
  7. 32
  8. 81
  9. 8.2
  10. 84
  11. 21
  12. 16
  13. 4.6
  14. 36
  15. 30
  16. 29
  17. 79
  18. 6.9
  19. 44
  20. 6.3
  21. 41
  22. 52
  23. 9.2
  24. 26
  25. 71
  26. 60
  27. 7.2
  28. 5.9
  29. 74
  30. 7.9
  31. 79
  32. 9.7
  33. 54
  34. 66
  35. 9.4
  36. 8.7
  37. 14
  38. 18
  39. 8.9
  40. 49

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