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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 453 · 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.√45 to 1 decimal place? (a) 6.8 (b) 6.7 (c) 6.5 (d) 6.6
  2. 2.Best estimate of 1598 ÷ 27? (a) 5300 (b) 53 (c) 530
  3. 3.√70 to 1 decimal place? (a) 8.5 (b) 8.3 (c) 8.6 (d) 8.4
  4. 4.√37 to 1 decimal place? (a) 6.2 (b) 6.1 (c) 6.3 (d) 6.4
  5. 5.Best estimate of 6678 ÷ 88? (a) 74 (b) 7400 (c) 740
  6. 6.√24 to 1 decimal place? (a) 4.9 (b) 5.0 (c) 4.8 (d) 4.7
  7. 7.Best estimate of 5068 ÷ 64? (a) 840 (b) 8400 (c) 84
  8. 8.Best estimate of 3497 ÷ 66? (a) 50 (b) 5000 (c) 500
  9. 9.Best estimate of 2337 ÷ 32? (a) 780 (b) 78 (c) 7800
  10. 10.Best estimate of 1355 ÷ 31? (a) 450 (b) 45 (c) 4500
  11. 11.Best estimate of 641 ÷ 27? (a) 21 (b) 210 (c) 2100
  12. 12.√96 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.9 (d) 10.0
  13. 13.Best estimate of 3095 ÷ 46? (a) 620 (b) 62 (c) 6200
  14. 14.Best estimate of 3211 ÷ 47? (a) 64 (b) 640 (c) 6400
  15. 15.Best estimate of 2864 ÷ 49? (a) 570 (b) 57 (c) 5700
  16. 16.Best estimate of 7032 ÷ 82? (a) 88 (b) 8800 (c) 880
  17. 17.Best estimate of 1812 ÷ 59? (a) 30 (b) 300 (c) 3000
  18. 18.√43 to 1 decimal place? (a) 6.7 (b) 6.5 (c) 6.4 (d) 6.6
  19. 19.√69 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.1 (d) 8.2
  20. 20.√94 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 10.0 (d) 9.9
  21. 21.Best estimate of 912 ÷ 28? (a) 300 (b) 30 (c) 3000
  22. 22.√59 to 1 decimal place? (a) 7.9 (b) 7.8 (c) 7.6 (d) 7.7
  23. 23.Best estimate of 4574 ÷ 68? (a) 65 (b) 650 (c) 6500
  24. 24.Best estimate of 2049 ÷ 84? (a) 26 (b) 2600 (c) 260
  25. 25.√31 to 1 decimal place? (a) 5.5 (b) 5.7 (c) 5.4 (d) 5.6
  26. 26.Best estimate of 4591 ÷ 76? (a) 57 (b) 570 (c) 5700
  27. 27.Best estimate of 1076 ÷ 21? (a) 540 (b) 5400 (c) 54
  28. 28.Best estimate of 994 ÷ 26? (a) 3300 (b) 330 (c) 33
  29. 29.√55 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.7 (d) 7.5
  30. 30.Best estimate of 592 ÷ 26? (a) 20 (b) 200 (c) 2000
  31. 31.√82 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.1 (d) 9.4
  32. 32.Best estimate of 6894 ÷ 82? (a) 86 (b) 8600 (c) 860
  33. 33.√66 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.1 (d) 8.0
  34. 34.Best estimate of 2170 ÷ 37? (a) 540 (b) 54 (c) 5400
  35. 35.Best estimate of 1834 ÷ 48? (a) 370 (b) 37 (c) 3700
  36. 36.Best estimate of 2643 ÷ 73? (a) 380 (b) 38 (c) 3800
  37. 37.Best estimate of 3925 ÷ 62? (a) 650 (b) 6500 (c) 65
  38. 38.Best estimate of 2918 ÷ 42? (a) 73 (b) 7300 (c) 730
  39. 39.Best estimate of 3172 ÷ 43? (a) 790 (b) 79 (c) 7900
  40. 40.Best estimate of 1789 ÷ 36? (a) 45 (b) 4500 (c) 450

Answer key

  1. 6.7
  2. 53
  3. 8.4
  4. 6.1
  5. 74
  6. 4.9
  7. 84
  8. 50
  9. 78
  10. 45
  11. 21
  12. 9.8
  13. 62
  14. 64
  15. 57
  16. 88
  17. 30
  18. 6.6
  19. 8.3
  20. 9.7
  21. 30
  22. 7.7
  23. 65
  24. 26
  25. 5.6
  26. 57
  27. 54
  28. 33
  29. 7.4
  30. 20
  31. 9.1
  32. 86
  33. 8.1
  34. 54
  35. 37
  36. 38
  37. 65
  38. 73
  39. 79
  40. 45

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