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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 981 · 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 7235 ÷ 78? (a) 900 (b) 90 (c) 9000
  2. 2.√98 to 1 decimal place? (a) 9.9 (b) 9.7 (c) 9.6 (d) 9.8
  3. 3.√76 to 1 decimal place? (a) 8.9 (b) 8.7 (c) 9.0 (d) 8.8
  4. 4.Best estimate of 1186 ÷ 42? (a) 3000 (b) 30 (c) 300
  5. 5.Best estimate of 557 ÷ 38? (a) 1400 (b) 14 (c) 140
  6. 6.Best estimate of 3045 ÷ 61? (a) 510 (b) 51 (c) 5100
  7. 7.√35 to 1 decimal place? (a) 6.2 (b) 6.0 (c) 5.9 (d) 6.1
  8. 8.Best estimate of 4394 ÷ 46? (a) 880 (b) 8800 (c) 88
  9. 9.√42 to 1 decimal place? (a) 6.7 (b) 6.6 (c) 6.5 (d) 6.4
  10. 10.Best estimate of 2470 ÷ 39? (a) 620 (b) 6200 (c) 62
  11. 11.Best estimate of 3470 ÷ 42? (a) 87 (b) 870 (c) 8700
  12. 12.√88 to 1 decimal place? (a) 9.6 (b) 9.4 (c) 9.5 (d) 9.3
  13. 13.Best estimate of 1108 ÷ 52? (a) 2200 (b) 22 (c) 220
  14. 14.√87 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.6 (d) 9.5
  15. 15.√96 to 1 decimal place? (a) 9.7 (b) 9.9 (c) 10.0 (d) 9.8
  16. 16.√90 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.3 (d) 9.6
  17. 17.Best estimate of 3990 ÷ 72? (a) 5700 (b) 570 (c) 57
  18. 18.Best estimate of 1690 ÷ 62? (a) 2800 (b) 280 (c) 28
  19. 19.√65 to 1 decimal place? (a) 8.0 (b) 8.2 (c) 7.9 (d) 8.1
  20. 20.Best estimate of 1860 ÷ 22? (a) 9300 (b) 93 (c) 930
  21. 21.Best estimate of 5409 ÷ 72? (a) 770 (b) 7700 (c) 77
  22. 22.Best estimate of 1613 ÷ 71? (a) 23 (b) 230 (c) 2300
  23. 23.√92 to 1 decimal place? (a) 9.7 (b) 9.9 (c) 9.8 (d) 9.6
  24. 24.√28 to 1 decimal place? (a) 5.3 (b) 5.2 (c) 5.1 (d) 5.4
  25. 25.√37 to 1 decimal place? (a) 6.1 (b) 5.9 (c) 6.2 (d) 6.0
  26. 26.√26 to 1 decimal place? (a) 5.2 (b) 5.1 (c) 5.4 (d) 5.3
  27. 27.Best estimate of 2446 ÷ 57? (a) 41 (b) 4100 (c) 410
  28. 28.√77 to 1 decimal place? (a) 8.9 (b) 8.7 (c) 8.8 (d) 9.0
  29. 29.Best estimate of 3843 ÷ 46? (a) 7700 (b) 770 (c) 77
  30. 30.Best estimate of 2244 ÷ 49? (a) 4500 (b) 45 (c) 450
  31. 31.√66 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.1 (d) 8.2
  32. 32.√40 to 1 decimal place? (a) 6.5 (b) 6.2 (c) 6.4 (d) 6.3
  33. 33.Best estimate of 2556 ÷ 32? (a) 850 (b) 8500 (c) 85
  34. 34.Best estimate of 2614 ÷ 78? (a) 33 (b) 3300 (c) 330
  35. 35.Best estimate of 661 ÷ 26? (a) 2200 (b) 22 (c) 220
  36. 36.√83 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.0 (d) 9.1
  37. 37.Best estimate of 2974 ÷ 39? (a) 74 (b) 7400 (c) 740
  38. 38.Best estimate of 3742 ÷ 86? (a) 420 (b) 4200 (c) 42
  39. 39.Best estimate of 5109 ÷ 54? (a) 102 (b) 10200 (c) 1020
  40. 40.Best estimate of 3555 ÷ 61? (a) 5900 (b) 590 (c) 59

Answer key

  1. 90
  2. 9.9
  3. 8.7
  4. 30
  5. 14
  6. 51
  7. 5.9
  8. 88
  9. 6.5
  10. 62
  11. 87
  12. 9.4
  13. 22
  14. 9.3
  15. 9.8
  16. 9.5
  17. 57
  18. 28
  19. 8.1
  20. 93
  21. 77
  22. 23
  23. 9.6
  24. 5.3
  25. 6.1
  26. 5.1
  27. 41
  28. 8.8
  29. 77
  30. 45
  31. 8.1
  32. 6.3
  33. 85
  34. 33
  35. 22
  36. 9.1
  37. 74
  38. 42
  39. 102
  40. 59

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