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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 208 · 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 2957 ÷ 64? (a) 490 (b) 4900 (c) 49
  2. 2.Best estimate of 1795 ÷ 39? (a) 450 (b) 45 (c) 4500
  3. 3.Best estimate of 1161 ÷ 22? (a) 580 (b) 5800 (c) 58
  4. 4.Best estimate of 888 ÷ 73? (a) 13 (b) 1300 (c) 130
  5. 5.√65 to 1 decimal place? (a) 8.4 (b) 8.1 (c) 8.2 (d) 8.3
  6. 6.Best estimate of 3386 ÷ 46? (a) 6800 (b) 680 (c) 68
  7. 7.Best estimate of 2597 ÷ 89? (a) 290 (b) 2900 (c) 29
  8. 8.√76 to 1 decimal place? (a) 9.0 (b) 8.7 (c) 8.8 (d) 8.9
  9. 9.Best estimate of 3602 ÷ 78? (a) 45 (b) 450 (c) 4500
  10. 10.√67 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.2 (d) 8.1
  11. 11.Best estimate of 1662 ÷ 36? (a) 42 (b) 4200 (c) 420
  12. 12.√43 to 1 decimal place? (a) 6.6 (b) 6.8 (c) 6.9 (d) 6.7
  13. 13.Best estimate of 2870 ÷ 34? (a) 960 (b) 9600 (c) 96
  14. 14.Best estimate of 1349 ÷ 21? (a) 67 (b) 6700 (c) 670
  15. 15.Best estimate of 2468 ÷ 87? (a) 2700 (b) 270 (c) 27
  16. 16.Best estimate of 1028 ÷ 42? (a) 260 (b) 2600 (c) 26
  17. 17.√62 to 1 decimal place? (a) 8.1 (b) 7.9 (c) 8.0 (d) 7.8
  18. 18.√94 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.7 (d) 9.6
  19. 19.√46 to 1 decimal place? (a) 6.8 (b) 6.6 (c) 6.5 (d) 6.7
  20. 20.Best estimate of 6057 ÷ 74? (a) 870 (b) 8700 (c) 87
  21. 21.√47 to 1 decimal place? (a) 6.8 (b) 7.1 (c) 7.0 (d) 6.9
  22. 22.√50 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.3 (d) 7.0
  23. 23.Best estimate of 6358 ÷ 69? (a) 91 (b) 9100 (c) 910
  24. 24.Best estimate of 1274 ÷ 41? (a) 3200 (b) 32 (c) 320
  25. 25.Best estimate of 2389 ÷ 31? (a) 8000 (b) 80 (c) 800
  26. 26.Best estimate of 2065 ÷ 24? (a) 103 (b) 1030 (c) 10300
  27. 27.√85 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.0 (d) 8.9
  28. 28.Best estimate of 2411 ÷ 54? (a) 48 (b) 4800 (c) 480
  29. 29.Best estimate of 1405 ÷ 29? (a) 4700 (b) 47 (c) 470
  30. 30.√61 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 7.6 (d) 7.9
  31. 31.Best estimate of 4541 ÷ 68? (a) 6500 (b) 650 (c) 65
  32. 32.Best estimate of 3607 ÷ 46? (a) 7200 (b) 720 (c) 72
  33. 33.Best estimate of 774 ÷ 46? (a) 150 (b) 1500 (c) 15
  34. 34.Best estimate of 3328 ÷ 44? (a) 830 (b) 83 (c) 8300
  35. 35.Best estimate of 862 ÷ 29? (a) 290 (b) 29 (c) 2900
  36. 36.Best estimate of 3762 ÷ 89? (a) 420 (b) 4200 (c) 42
  37. 37.Best estimate of 490 ÷ 36? (a) 120 (b) 1200 (c) 12
  38. 38.Best estimate of 612 ÷ 41? (a) 15 (b) 1500 (c) 150
  39. 39.Best estimate of 3309 ÷ 84? (a) 4100 (b) 41 (c) 410
  40. 40.Best estimate of 5680 ÷ 77? (a) 71 (b) 7100 (c) 710

Answer key

  1. 49
  2. 45
  3. 58
  4. 13
  5. 8.1
  6. 68
  7. 29
  8. 8.7
  9. 45
  10. 8.2
  11. 42
  12. 6.6
  13. 96
  14. 67
  15. 27
  16. 26
  17. 7.9
  18. 9.7
  19. 6.8
  20. 87
  21. 6.9
  22. 7.1
  23. 91
  24. 32
  25. 80
  26. 103
  27. 9.2
  28. 48
  29. 47
  30. 7.8
  31. 65
  32. 72
  33. 15
  34. 83
  35. 29
  36. 42
  37. 12
  38. 15
  39. 41
  40. 71

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