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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 324 · 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.√46 to 1 decimal place? (a) 6.8 (b) 6.5 (c) 6.6 (d) 6.7
  2. 2.Best estimate of 4080 ÷ 63? (a) 68 (b) 680 (c) 6800
  3. 3.Best estimate of 5536 ÷ 59? (a) 920 (b) 92 (c) 9200
  4. 4.Best estimate of 6179 ÷ 81? (a) 77 (b) 770 (c) 7700
  5. 5.Best estimate of 4695 ÷ 64? (a) 7800 (b) 780 (c) 78
  6. 6.Best estimate of 2660 ÷ 47? (a) 53 (b) 5300 (c) 530
  7. 7.√30 to 1 decimal place? (a) 5.3 (b) 5.2 (c) 5.5 (d) 5.4
  8. 8.Best estimate of 594 ÷ 26? (a) 200 (b) 2000 (c) 20
  9. 9.Best estimate of 4543 ÷ 62? (a) 7600 (b) 76 (c) 760
  10. 10.Best estimate of 6772 ÷ 76? (a) 8500 (b) 85 (c) 850
  11. 11.√58 to 1 decimal place? (a) 7.6 (b) 7.3 (c) 7.5 (d) 7.4
  12. 12.Best estimate of 6086 ÷ 87? (a) 68 (b) 680 (c) 6800
  13. 13.Best estimate of 1517 ÷ 81? (a) 19 (b) 1900 (c) 190
  14. 14.Best estimate of 1910 ÷ 33? (a) 64 (b) 640 (c) 6400
  15. 15.Best estimate of 2207 ÷ 32? (a) 74 (b) 740 (c) 7400
  16. 16.Best estimate of 1173 ÷ 51? (a) 2300 (b) 230 (c) 23
  17. 17.√92 to 1 decimal place? (a) 9.6 (b) 9.9 (c) 9.8 (d) 9.7
  18. 18.√69 to 1 decimal place? (a) 8.6 (b) 8.3 (c) 8.5 (d) 8.4
  19. 19.Best estimate of 3494 ÷ 71? (a) 5000 (b) 500 (c) 50
  20. 20.√90 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.5 (d) 9.3
  21. 21.Best estimate of 1341 ÷ 49? (a) 27 (b) 270 (c) 2700
  22. 22.Best estimate of 5839 ÷ 89? (a) 65 (b) 6500 (c) 650
  23. 23.Best estimate of 1158 ÷ 44? (a) 2900 (b) 290 (c) 29
  24. 24.Best estimate of 956 ÷ 58? (a) 1600 (b) 16 (c) 160
  25. 25.Best estimate of 6310 ÷ 76? (a) 7900 (b) 790 (c) 79
  26. 26.√55 to 1 decimal place? (a) 7.5 (b) 7.3 (c) 7.2 (d) 7.4
  27. 27.Best estimate of 5974 ÷ 72? (a) 8500 (b) 850 (c) 85
  28. 28.√40 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.5 (d) 6.6
  29. 29.√66 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 8.3 (d) 8.0
  30. 30.√24 to 1 decimal place? (a) 4.9 (b) 5.1 (c) 4.8 (d) 5.0
  31. 31.Best estimate of 2527 ÷ 29? (a) 840 (b) 84 (c) 8400
  32. 32.√53 to 1 decimal place? (a) 7.2 (b) 7.4 (c) 7.1 (d) 7.3
  33. 33.Best estimate of 1081 ÷ 44? (a) 270 (b) 2700 (c) 27
  34. 34.Best estimate of 4805 ÷ 57? (a) 80 (b) 800 (c) 8000
  35. 35.Best estimate of 1115 ÷ 32? (a) 3700 (b) 37 (c) 370
  36. 36.Best estimate of 2933 ÷ 72? (a) 4200 (b) 420 (c) 42
  37. 37.Best estimate of 3635 ÷ 77? (a) 4500 (b) 45 (c) 450
  38. 38.√21 to 1 decimal place? (a) 4.6 (b) 4.8 (c) 4.9 (d) 4.7
  39. 39.√37 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.0 (d) 6.1
  40. 40.Best estimate of 2154 ÷ 39? (a) 540 (b) 54 (c) 5400

Answer key

  1. 6.8
  2. 68
  3. 92
  4. 77
  5. 78
  6. 53
  7. 5.5
  8. 20
  9. 76
  10. 85
  11. 7.6
  12. 68
  13. 19
  14. 64
  15. 74
  16. 23
  17. 9.6
  18. 8.3
  19. 50
  20. 9.5
  21. 27
  22. 65
  23. 29
  24. 16
  25. 79
  26. 7.4
  27. 85
  28. 6.3
  29. 8.1
  30. 4.9
  31. 84
  32. 7.3
  33. 27
  34. 80
  35. 37
  36. 42
  37. 45
  38. 4.6
  39. 6.1
  40. 54

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