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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 629 · 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 2160 ÷ 88? (a) 24 (b) 2400 (c) 240
  2. 2.Best estimate of 1306 ÷ 52? (a) 260 (b) 2600 (c) 26
  3. 3.√59 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 8.0 (d) 7.9
  4. 4.Best estimate of 4310 ÷ 48? (a) 8600 (b) 860 (c) 86
  5. 5.Best estimate of 2870 ÷ 77? (a) 360 (b) 36 (c) 3600
  6. 6.√43 to 1 decimal place? (a) 6.4 (b) 6.5 (c) 6.3 (d) 6.6
  7. 7.√37 to 1 decimal place? (a) 5.9 (b) 6.1 (c) 6.0 (d) 5.8
  8. 8.√82 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 9.3 (d) 9.2
  9. 9.Best estimate of 2505 ÷ 66? (a) 3600 (b) 36 (c) 360
  10. 10.√55 to 1 decimal place? (a) 7.5 (b) 7.3 (c) 7.6 (d) 7.4
  11. 11.√77 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.8 (d) 8.5
  12. 12.Best estimate of 1310 ÷ 22? (a) 6600 (b) 66 (c) 660
  13. 13.√35 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 5.9 (d) 6.0
  14. 14.√56 to 1 decimal place? (a) 7.7 (b) 7.5 (c) 7.8 (d) 7.6
  15. 15.√21 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 4.9 (d) 4.6
  16. 16.√67 to 1 decimal place? (a) 8.3 (b) 8.5 (c) 8.4 (d) 8.2
  17. 17.Best estimate of 2723 ÷ 32? (a) 9100 (b) 910 (c) 91
  18. 18.√66 to 1 decimal place? (a) 8.1 (b) 7.8 (c) 8.0 (d) 7.9
  19. 19.Best estimate of 743 ÷ 23? (a) 3700 (b) 370 (c) 37
  20. 20.√90 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.4 (d) 9.7
  21. 21.Best estimate of 3549 ÷ 68? (a) 5100 (b) 51 (c) 510
  22. 22.Best estimate of 3516 ÷ 53? (a) 70 (b) 7000 (c) 700
  23. 23.√28 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.3 (d) 5.4
  24. 24.√96 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.9 (d) 10.0
  25. 25.Best estimate of 2149 ÷ 27? (a) 7200 (b) 72 (c) 720
  26. 26.√98 to 1 decimal place? (a) 9.8 (b) 10.0 (c) 10.1 (d) 9.9
  27. 27.Best estimate of 4260 ÷ 84? (a) 5300 (b) 530 (c) 53
  28. 28.√85 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.1 (d) 9.4
  29. 29.√92 to 1 decimal place? (a) 9.9 (b) 9.7 (c) 9.8 (d) 9.6
  30. 30.Best estimate of 1403 ÷ 32? (a) 470 (b) 47 (c) 4700
  31. 31.Best estimate of 4907 ÷ 73? (a) 70 (b) 7000 (c) 700
  32. 32.√94 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.7 (d) 9.4
  33. 33.Best estimate of 3701 ÷ 42? (a) 9300 (b) 93 (c) 930
  34. 34.Best estimate of 2183 ÷ 27? (a) 73 (b) 730 (c) 7300
  35. 35.Best estimate of 2655 ÷ 68? (a) 380 (b) 3800 (c) 38
  36. 36.Best estimate of 1006 ÷ 27? (a) 340 (b) 3400 (c) 34
  37. 37.Best estimate of 1418 ÷ 66? (a) 20 (b) 2000 (c) 200
  38. 38.Best estimate of 4431 ÷ 48? (a) 8900 (b) 89 (c) 890
  39. 39.Best estimate of 2884 ÷ 46? (a) 580 (b) 58 (c) 5800
  40. 40.√78 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.8 (d) 8.9

Answer key

  1. 24
  2. 26
  3. 7.7
  4. 86
  5. 36
  6. 6.6
  7. 6.1
  8. 9.1
  9. 36
  10. 7.4
  11. 8.8
  12. 66
  13. 5.9
  14. 7.5
  15. 4.6
  16. 8.2
  17. 91
  18. 8.1
  19. 37
  20. 9.5
  21. 51
  22. 70
  23. 5.3
  24. 9.8
  25. 72
  26. 9.9
  27. 53
  28. 9.2
  29. 9.6
  30. 47
  31. 70
  32. 9.7
  33. 93
  34. 73
  35. 38
  36. 34
  37. 20
  38. 89
  39. 58
  40. 8.8

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