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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 374 · 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 3914 ÷ 43? (a) 980 (b) 98 (c) 9800
  2. 2.√41 to 1 decimal place? (a) 6.5 (b) 6.7 (c) 6.6 (d) 6.4
  3. 3.√75 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 8.7 (d) 8.8
  4. 4.Best estimate of 748 ÷ 27? (a) 250 (b) 2500 (c) 25
  5. 5.√90 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.3 (d) 9.4
  6. 6.√51 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.1 (d) 7.2
  7. 7.Best estimate of 2231 ÷ 74? (a) 320 (b) 3200 (c) 32
  8. 8.Best estimate of 591 ÷ 38? (a) 1500 (b) 15 (c) 150
  9. 9.√62 to 1 decimal place? (a) 8.2 (b) 7.9 (c) 8.0 (d) 8.1
  10. 10.Best estimate of 2633 ÷ 32? (a) 880 (b) 88 (c) 8800
  11. 11.√20 to 1 decimal place? (a) 4.4 (b) 4.5 (c) 4.3 (d) 4.2
  12. 12.Best estimate of 2455 ÷ 29? (a) 820 (b) 8200 (c) 82
  13. 13.√26 to 1 decimal place? (a) 5.2 (b) 5.4 (c) 5.1 (d) 5.3
  14. 14.Best estimate of 1770 ÷ 56? (a) 30 (b) 3000 (c) 300
  15. 15.Best estimate of 714 ÷ 31? (a) 2400 (b) 240 (c) 24
  16. 16.√94 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.8 (d) 9.9
  17. 17.√37 to 1 decimal place? (a) 6.0 (b) 6.1 (c) 5.8 (d) 5.9
  18. 18.Best estimate of 6682 ÷ 81? (a) 8400 (b) 840 (c) 84
  19. 19.Best estimate of 4147 ÷ 66? (a) 590 (b) 5900 (c) 59
  20. 20.Best estimate of 2044 ÷ 44? (a) 51 (b) 5100 (c) 510
  21. 21.Best estimate of 2222 ÷ 89? (a) 2500 (b) 25 (c) 250
  22. 22.Best estimate of 3955 ÷ 63? (a) 6600 (b) 66 (c) 660
  23. 23.Best estimate of 2623 ÷ 34? (a) 87 (b) 870 (c) 8700
  24. 24.√46 to 1 decimal place? (a) 7.0 (b) 6.9 (c) 6.8 (d) 7.1
  25. 25.√24 to 1 decimal place? (a) 5.0 (b) 5.1 (c) 4.9 (d) 5.2
  26. 26.√79 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 8.9 (d) 9.0
  27. 27.√59 to 1 decimal place? (a) 7.9 (b) 7.8 (c) 7.7 (d) 7.6
  28. 28.Best estimate of 3307 ÷ 76? (a) 410 (b) 4100 (c) 41
  29. 29.Best estimate of 1411 ÷ 23? (a) 71 (b) 7100 (c) 710
  30. 30.Best estimate of 5739 ÷ 72? (a) 82 (b) 820 (c) 8200
  31. 31.Best estimate of 4382 ÷ 77? (a) 5500 (b) 55 (c) 550
  32. 32.Best estimate of 1483 ÷ 46? (a) 3000 (b) 300 (c) 30
  33. 33.Best estimate of 881 ÷ 68? (a) 130 (b) 1300 (c) 13
  34. 34.Best estimate of 1698 ÷ 88? (a) 19 (b) 1900 (c) 190
  35. 35.Best estimate of 5886 ÷ 88? (a) 650 (b) 6500 (c) 65
  36. 36.Best estimate of 6140 ÷ 68? (a) 88 (b) 8800 (c) 880
  37. 37.Best estimate of 1531 ÷ 26? (a) 5100 (b) 51 (c) 510
  38. 38.√86 to 1 decimal place? (a) 9.2 (b) 9.4 (c) 9.5 (d) 9.3
  39. 39.Best estimate of 1797 ÷ 59? (a) 300 (b) 3000 (c) 30
  40. 40.√66 to 1 decimal place? (a) 8.3 (b) 8.1 (c) 8.2 (d) 8.4

Answer key

  1. 98
  2. 6.4
  3. 8.7
  4. 25
  5. 9.5
  6. 7.1
  7. 32
  8. 15
  9. 7.9
  10. 88
  11. 4.5
  12. 82
  13. 5.1
  14. 30
  15. 24
  16. 9.7
  17. 6.1
  18. 84
  19. 59
  20. 51
  21. 25
  22. 66
  23. 87
  24. 6.8
  25. 4.9
  26. 8.9
  27. 7.7
  28. 41
  29. 71
  30. 82
  31. 55
  32. 30
  33. 13
  34. 19
  35. 65
  36. 88
  37. 51
  38. 9.3
  39. 30
  40. 8.1

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