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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 469 · 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 7100 ÷ 83? (a) 890 (b) 89 (c) 8900
  2. 2.Best estimate of 6347 ÷ 72? (a) 9100 (b) 91 (c) 910
  3. 3.Best estimate of 5777 ÷ 86? (a) 64 (b) 6400 (c) 640
  4. 4.√71 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.4 (d) 8.5
  5. 5.√90 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.6 (d) 9.5
  6. 6.√45 to 1 decimal place? (a) 6.4 (b) 6.7 (c) 6.5 (d) 6.6
  7. 7.Best estimate of 3340 ÷ 84? (a) 42 (b) 4200 (c) 420
  8. 8.√26 to 1 decimal place? (a) 5.1 (b) 5.2 (c) 5.4 (d) 5.3
  9. 9.Best estimate of 2425 ÷ 86? (a) 27 (b) 2700 (c) 270
  10. 10.√70 to 1 decimal place? (a) 8.3 (b) 8.1 (c) 8.4 (d) 8.2
  11. 11.√34 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 6.1 (d) 5.8
  12. 12.√20 to 1 decimal place? (a) 4.5 (b) 4.3 (c) 4.6 (d) 4.4
  13. 13.Best estimate of 928 ÷ 37? (a) 230 (b) 2300 (c) 23
  14. 14.√75 to 1 decimal place? (a) 8.8 (b) 8.5 (c) 8.6 (d) 8.7
  15. 15.√78 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 8.8 (d) 8.9
  16. 16.Best estimate of 3000 ÷ 42? (a) 75 (b) 750 (c) 7500
  17. 17.Best estimate of 2764 ÷ 51? (a) 5500 (b) 55 (c) 550
  18. 18.Best estimate of 3839 ÷ 66? (a) 55 (b) 550 (c) 5500
  19. 19.√23 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 4.7 (d) 4.8
  20. 20.Best estimate of 2187 ÷ 56? (a) 36 (b) 3600 (c) 360
  21. 21.√77 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.8 (d) 8.9
  22. 22.Best estimate of 4263 ÷ 52? (a) 850 (b) 85 (c) 8500
  23. 23.√46 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 6.7 (d) 6.6
  24. 24.√69 to 1 decimal place? (a) 8.5 (b) 8.3 (c) 8.6 (d) 8.4
  25. 25.Best estimate of 1911 ÷ 36? (a) 480 (b) 4800 (c) 48
  26. 26.√80 to 1 decimal place? (a) 8.9 (b) 8.6 (c) 8.8 (d) 8.7
  27. 27.√56 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.5 (d) 7.3
  28. 28.Best estimate of 4918 ÷ 52? (a) 980 (b) 9800 (c) 98
  29. 29.√79 to 1 decimal place? (a) 8.9 (b) 9.1 (c) 8.8 (d) 9.0
  30. 30.√28 to 1 decimal place? (a) 5.2 (b) 5.4 (c) 5.3 (d) 5.1
  31. 31.Best estimate of 2045 ÷ 42? (a) 5100 (b) 510 (c) 51
  32. 32.Best estimate of 2822 ÷ 79? (a) 3500 (b) 350 (c) 35
  33. 33.√40 to 1 decimal place? (a) 6.3 (b) 6.5 (c) 6.2 (d) 6.4
  34. 34.Best estimate of 2493 ÷ 33? (a) 83 (b) 8300 (c) 830
  35. 35.√63 to 1 decimal place? (a) 7.8 (b) 8.0 (c) 8.1 (d) 7.9
  36. 36.Best estimate of 3803 ÷ 46? (a) 760 (b) 76 (c) 7600
  37. 37.√84 to 1 decimal place? (a) 9.3 (b) 9.5 (c) 9.4 (d) 9.2
  38. 38.Best estimate of 3071 ÷ 72? (a) 440 (b) 4400 (c) 44
  39. 39.Best estimate of 4196 ÷ 69? (a) 6000 (b) 60 (c) 600
  40. 40.Best estimate of 6117 ÷ 72? (a) 87 (b) 8700 (c) 870

Answer key

  1. 89
  2. 91
  3. 64
  4. 8.4
  5. 9.5
  6. 6.7
  7. 42
  8. 5.1
  9. 27
  10. 8.4
  11. 5.8
  12. 4.5
  13. 23
  14. 8.7
  15. 8.8
  16. 75
  17. 55
  18. 55
  19. 4.8
  20. 36
  21. 8.8
  22. 85
  23. 6.8
  24. 8.3
  25. 48
  26. 8.9
  27. 7.5
  28. 98
  29. 8.9
  30. 5.3
  31. 51
  32. 35
  33. 6.3
  34. 83
  35. 7.9
  36. 76
  37. 9.2
  38. 44
  39. 60
  40. 87

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