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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 566 · 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 3126 ÷ 33? (a) 104 (b) 1040 (c) 10400
  2. 2.√41 to 1 decimal place? (a) 6.3 (b) 6.1 (c) 6.4 (d) 6.2
  3. 3.√48 to 1 decimal place? (a) 7.0 (b) 7.1 (c) 6.9 (d) 7.2
  4. 4.Best estimate of 2668 ÷ 42? (a) 670 (b) 6700 (c) 67
  5. 5.Best estimate of 2173 ÷ 23? (a) 109 (b) 1090 (c) 10900
  6. 6.Best estimate of 4811 ÷ 63? (a) 800 (b) 80 (c) 8000
  7. 7.√66 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 8.2 (d) 8.3
  8. 8.Best estimate of 2628 ÷ 39? (a) 660 (b) 6600 (c) 66
  9. 9.Best estimate of 774 ÷ 59? (a) 13 (b) 130 (c) 1300
  10. 10.√21 to 1 decimal place? (a) 4.7 (b) 4.5 (c) 4.8 (d) 4.6
  11. 11.√42 to 1 decimal place? (a) 6.7 (b) 6.5 (c) 6.8 (d) 6.6
  12. 12.Best estimate of 493 ÷ 28? (a) 160 (b) 16 (c) 1600
  13. 13.Best estimate of 2424 ÷ 33? (a) 8100 (b) 81 (c) 810
  14. 14.√58 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.4 (d) 7.5
  15. 15.Best estimate of 1792 ÷ 66? (a) 2600 (b) 260 (c) 26
  16. 16.Best estimate of 2348 ÷ 62? (a) 39 (b) 3900 (c) 390
  17. 17.√61 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 7.8 (d) 7.9
  18. 18.Best estimate of 1779 ÷ 83? (a) 2200 (b) 22 (c) 220
  19. 19.√37 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.4 (d) 6.1
  20. 20.Best estimate of 2515 ÷ 62? (a) 420 (b) 42 (c) 4200
  21. 21.Best estimate of 570 ÷ 28? (a) 19 (b) 1900 (c) 190
  22. 22.√26 to 1 decimal place? (a) 5.3 (b) 5.4 (c) 5.1 (d) 5.2
  23. 23.Best estimate of 5770 ÷ 66? (a) 8200 (b) 820 (c) 82
  24. 24.Best estimate of 4338 ÷ 82? (a) 5400 (b) 54 (c) 540
  25. 25.√90 to 1 decimal place? (a) 9.3 (b) 9.6 (c) 9.4 (d) 9.5
  26. 26.Best estimate of 2598 ÷ 52? (a) 520 (b) 5200 (c) 52
  27. 27.Best estimate of 1467 ÷ 66? (a) 210 (b) 2100 (c) 21
  28. 28.Best estimate of 1564 ÷ 84? (a) 20 (b) 2000 (c) 200
  29. 29.Best estimate of 2055 ÷ 32? (a) 690 (b) 6900 (c) 69
  30. 30.√52 to 1 decimal place? (a) 7.1 (b) 7.0 (c) 7.2 (d) 6.9
  31. 31.Best estimate of 2079 ÷ 32? (a) 6900 (b) 69 (c) 690
  32. 32.√82 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 9.3 (d) 9.2
  33. 33.Best estimate of 1415 ÷ 47? (a) 28 (b) 280 (c) 2800
  34. 34.Best estimate of 6288 ÷ 84? (a) 7900 (b) 790 (c) 79
  35. 35.Best estimate of 1523 ÷ 58? (a) 250 (b) 25 (c) 2500
  36. 36.√40 to 1 decimal place? (a) 6.3 (b) 6.6 (c) 6.4 (d) 6.5
  37. 37.Best estimate of 495 ÷ 36? (a) 120 (b) 12 (c) 1200
  38. 38.Best estimate of 1761 ÷ 48? (a) 350 (b) 35 (c) 3500
  39. 39.Best estimate of 3263 ÷ 37? (a) 82 (b) 820 (c) 8200
  40. 40.√34 to 1 decimal place? (a) 5.9 (b) 5.7 (c) 6.0 (d) 5.8

Answer key

  1. 104
  2. 6.4
  3. 6.9
  4. 67
  5. 109
  6. 80
  7. 8.1
  8. 66
  9. 13
  10. 4.6
  11. 6.5
  12. 16
  13. 81
  14. 7.6
  15. 26
  16. 39
  17. 7.8
  18. 22
  19. 6.1
  20. 42
  21. 19
  22. 5.1
  23. 82
  24. 54
  25. 9.5
  26. 52
  27. 21
  28. 20
  29. 69
  30. 7.2
  31. 69
  32. 9.1
  33. 28
  34. 79
  35. 25
  36. 6.3
  37. 12
  38. 35
  39. 82
  40. 5.8

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