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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 774 · 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 2430 ÷ 82? (a) 3000 (b) 30 (c) 300
  2. 2.√26 to 1 decimal place? (a) 5.1 (b) 5.0 (c) 4.8 (d) 4.9
  3. 3.Best estimate of 1982 ÷ 32? (a) 6600 (b) 66 (c) 660
  4. 4.Best estimate of 7482 ÷ 78? (a) 940 (b) 9400 (c) 94
  5. 5.√35 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 5.7 (d) 5.8
  6. 6.√50 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 7.4 (d) 7.3
  7. 7.Best estimate of 3162 ÷ 39? (a) 7900 (b) 79 (c) 790
  8. 8.Best estimate of 5725 ÷ 82? (a) 720 (b) 7200 (c) 72
  9. 9.√94 to 1 decimal place? (a) 9.9 (b) 9.7 (c) 9.8 (d) 10.0
  10. 10.Best estimate of 5093 ÷ 58? (a) 850 (b) 8500 (c) 85
  11. 11.Best estimate of 2620 ÷ 39? (a) 660 (b) 6600 (c) 66
  12. 12.√65 to 1 decimal place? (a) 8.3 (b) 8.1 (c) 8.4 (d) 8.2
  13. 13.Best estimate of 7950 ÷ 88? (a) 88 (b) 8800 (c) 880
  14. 14.Best estimate of 548 ÷ 22? (a) 270 (b) 27 (c) 2700
  15. 15.√66 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.2 (d) 8.1
  16. 16.√62 to 1 decimal place? (a) 7.9 (b) 7.7 (c) 7.8 (d) 8.0
  17. 17.Best estimate of 1308 ÷ 53? (a) 26 (b) 2600 (c) 260
  18. 18.√40 to 1 decimal place? (a) 6.6 (b) 6.4 (c) 6.3 (d) 6.5
  19. 19.Best estimate of 2025 ÷ 84? (a) 2500 (b) 250 (c) 25
  20. 20.Best estimate of 6746 ÷ 88? (a) 7500 (b) 750 (c) 75
  21. 21.Best estimate of 6392 ÷ 82? (a) 8000 (b) 80 (c) 800
  22. 22.Best estimate of 5070 ÷ 76? (a) 6300 (b) 63 (c) 630
  23. 23.Best estimate of 1080 ÷ 39? (a) 27 (b) 2700 (c) 270
  24. 24.√31 to 1 decimal place? (a) 5.7 (b) 5.9 (c) 5.6 (d) 5.8
  25. 25.Best estimate of 1838 ÷ 22? (a) 92 (b) 920 (c) 9200
  26. 26.√24 to 1 decimal place? (a) 4.8 (b) 5.0 (c) 4.7 (d) 4.9
  27. 27.√74 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.7 (d) 8.4
  28. 28.√61 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 8.0 (d) 7.7
  29. 29.Best estimate of 975 ÷ 36? (a) 240 (b) 24 (c) 2400
  30. 30.Best estimate of 4356 ÷ 76? (a) 54 (b) 5400 (c) 540
  31. 31.√34 to 1 decimal place? (a) 5.9 (b) 5.8 (c) 6.0 (d) 6.1
  32. 32.Best estimate of 647 ÷ 21? (a) 32 (b) 320 (c) 3200
  33. 33.√69 to 1 decimal place? (a) 8.2 (b) 8.0 (c) 8.1 (d) 8.3
  34. 34.√29 to 1 decimal place? (a) 5.3 (b) 5.5 (c) 5.4 (d) 5.2
  35. 35.√79 to 1 decimal place? (a) 9.0 (b) 9.2 (c) 9.1 (d) 8.9
  36. 36.√32 to 1 decimal place? (a) 5.5 (b) 5.4 (c) 5.6 (d) 5.7
  37. 37.√59 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.6 (d) 7.9
  38. 38.Best estimate of 3946 ÷ 56? (a) 660 (b) 6600 (c) 66
  39. 39.Best estimate of 995 ÷ 36? (a) 2500 (b) 250 (c) 25
  40. 40.√90 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.8 (d) 9.7

Answer key

  1. 30
  2. 5.1
  3. 66
  4. 94
  5. 5.9
  6. 7.1
  7. 79
  8. 72
  9. 9.7
  10. 85
  11. 66
  12. 8.1
  13. 88
  14. 27
  15. 8.1
  16. 7.9
  17. 26
  18. 6.3
  19. 25
  20. 75
  21. 80
  22. 63
  23. 27
  24. 5.6
  25. 92
  26. 4.9
  27. 8.6
  28. 7.8
  29. 24
  30. 54
  31. 5.8
  32. 32
  33. 8.3
  34. 5.4
  35. 8.9
  36. 5.7
  37. 7.7
  38. 66
  39. 25
  40. 9.5

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