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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 548 · 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 1188 ÷ 48? (a) 2400 (b) 240 (c) 24
  2. 2.Best estimate of 4005 ÷ 52? (a) 80 (b) 800 (c) 8000
  3. 3.Best estimate of 4690 ÷ 62? (a) 78 (b) 7800 (c) 780
  4. 4.√92 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.9 (d) 9.7
  5. 5.√67 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.4 (d) 8.5
  6. 6.Best estimate of 2520 ÷ 39? (a) 6300 (b) 63 (c) 630
  7. 7.Best estimate of 3491 ÷ 51? (a) 7000 (b) 70 (c) 700
  8. 8.Best estimate of 4034 ÷ 51? (a) 81 (b) 8100 (c) 810
  9. 9.√47 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 7.0 (d) 6.7
  10. 10.√26 to 1 decimal place? (a) 5.1 (b) 5.4 (c) 5.2 (d) 5.3
  11. 11.√61 to 1 decimal place? (a) 8.0 (b) 7.8 (c) 7.7 (d) 7.9
  12. 12.Best estimate of 5431 ÷ 84? (a) 68 (b) 680 (c) 6800
  13. 13.Best estimate of 7228 ÷ 82? (a) 9000 (b) 900 (c) 90
  14. 14.Best estimate of 4426 ÷ 88? (a) 49 (b) 490 (c) 4900
  15. 15.√96 to 1 decimal place? (a) 9.7 (b) 9.9 (c) 9.6 (d) 9.8
  16. 16.Best estimate of 5118 ÷ 73? (a) 73 (b) 730 (c) 7300
  17. 17.Best estimate of 1552 ÷ 21? (a) 780 (b) 7800 (c) 78
  18. 18.√86 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.3 (d) 9.6
  19. 19.Best estimate of 2301 ÷ 59? (a) 38 (b) 380 (c) 3800
  20. 20.Best estimate of 2950 ÷ 32? (a) 9800 (b) 98 (c) 980
  21. 21.Best estimate of 2569 ÷ 42? (a) 640 (b) 6400 (c) 64
  22. 22.Best estimate of 1870 ÷ 42? (a) 47 (b) 470 (c) 4700
  23. 23.√23 to 1 decimal place? (a) 4.8 (b) 4.9 (c) 5.0 (d) 4.7
  24. 24.√37 to 1 decimal place? (a) 6.0 (b) 6.1 (c) 6.3 (d) 6.2
  25. 25.Best estimate of 6128 ÷ 82? (a) 770 (b) 77 (c) 7700
  26. 26.√28 to 1 decimal place? (a) 5.6 (b) 5.4 (c) 5.3 (d) 5.5
  27. 27.√59 to 1 decimal place? (a) 7.6 (b) 7.9 (c) 7.8 (d) 7.7
  28. 28.Best estimate of 4947 ÷ 78? (a) 620 (b) 62 (c) 6200
  29. 29.Best estimate of 1378 ÷ 21? (a) 69 (b) 6900 (c) 690
  30. 30.√90 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.4 (d) 9.5
  31. 31.Best estimate of 3617 ÷ 66? (a) 520 (b) 52 (c) 5200
  32. 32.Best estimate of 3381 ÷ 76? (a) 420 (b) 42 (c) 4200
  33. 33.√82 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 8.9 (d) 9.2
  34. 34.√65 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.1 (d) 8.4
  35. 35.√27 to 1 decimal place? (a) 5.0 (b) 5.2 (c) 4.9 (d) 5.1
  36. 36.Best estimate of 1567 ÷ 57? (a) 2600 (b) 26 (c) 260
  37. 37.Best estimate of 1608 ÷ 56? (a) 270 (b) 2700 (c) 27
  38. 38.√29 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.2 (d) 5.5
  39. 39.Best estimate of 444 ÷ 28? (a) 15 (b) 150 (c) 1500
  40. 40.Best estimate of 2687 ÷ 56? (a) 45 (b) 4500 (c) 450

Answer key

  1. 24
  2. 80
  3. 78
  4. 9.6
  5. 8.2
  6. 63
  7. 70
  8. 81
  9. 6.9
  10. 5.1
  11. 7.8
  12. 68
  13. 90
  14. 49
  15. 9.8
  16. 73
  17. 78
  18. 9.3
  19. 38
  20. 98
  21. 64
  22. 47
  23. 4.8
  24. 6.1
  25. 77
  26. 5.3
  27. 7.7
  28. 62
  29. 69
  30. 9.5
  31. 52
  32. 42
  33. 9.1
  34. 8.1
  35. 5.2
  36. 26
  37. 27
  38. 5.4
  39. 15
  40. 45

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