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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 514 · 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 1973 ÷ 66? (a) 280 (b) 2800 (c) 28
  2. 2.√21 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.5 (d) 4.4
  3. 3.√20 to 1 decimal place? (a) 4.6 (b) 4.5 (c) 4.4 (d) 4.3
  4. 4.√85 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.3 (d) 9.4
  5. 5.Best estimate of 7660 ÷ 82? (a) 96 (b) 9600 (c) 960
  6. 6.√65 to 1 decimal place? (a) 8.0 (b) 8.2 (c) 7.9 (d) 8.1
  7. 7.Best estimate of 2759 ÷ 57? (a) 4600 (b) 46 (c) 460
  8. 8.√94 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 9.7 (d) 9.6
  9. 9.Best estimate of 2511 ÷ 81? (a) 3100 (b) 31 (c) 310
  10. 10.√29 to 1 decimal place? (a) 5.3 (b) 5.4 (c) 5.6 (d) 5.5
  11. 11.√83 to 1 decimal place? (a) 9.1 (b) 8.8 (c) 8.9 (d) 9.0
  12. 12.Best estimate of 2810 ÷ 62? (a) 4700 (b) 47 (c) 470
  13. 13.Best estimate of 7353 ÷ 87? (a) 8200 (b) 82 (c) 820
  14. 14.Best estimate of 502 ÷ 21? (a) 2500 (b) 25 (c) 250
  15. 15.Best estimate of 1119 ÷ 57? (a) 19 (b) 190 (c) 1900
  16. 16.√50 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.0 (d) 7.3
  17. 17.Best estimate of 743 ÷ 52? (a) 1500 (b) 150 (c) 15
  18. 18.Best estimate of 2969 ÷ 46? (a) 590 (b) 5900 (c) 59
  19. 19.√40 to 1 decimal place? (a) 6.2 (b) 6.0 (c) 6.3 (d) 6.1
  20. 20.Best estimate of 358 ÷ 23? (a) 1800 (b) 180 (c) 18
  21. 21.Best estimate of 455 ÷ 31? (a) 150 (b) 15 (c) 1500
  22. 22.√88 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.6 (d) 9.3
  23. 23.√30 to 1 decimal place? (a) 5.5 (b) 5.3 (c) 5.2 (d) 5.4
  24. 24.Best estimate of 1065 ÷ 32? (a) 360 (b) 3600 (c) 36
  25. 25.√82 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 8.8 (d) 9.1
  26. 26.√55 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.5 (d) 7.3
  27. 27.√62 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 8.2 (d) 8.1
  28. 28.Best estimate of 2748 ÷ 29? (a) 92 (b) 920 (c) 9200
  29. 29.Best estimate of 677 ÷ 38? (a) 170 (b) 1700 (c) 17
  30. 30.Best estimate of 4119 ÷ 44? (a) 10300 (b) 103 (c) 1030
  31. 31.Best estimate of 5728 ÷ 86? (a) 64 (b) 640 (c) 6400
  32. 32.√43 to 1 decimal place? (a) 6.7 (b) 6.9 (c) 6.6 (d) 6.8
  33. 33.Best estimate of 1509 ÷ 61? (a) 25 (b) 250 (c) 2500
  34. 34.Best estimate of 4895 ÷ 64? (a) 82 (b) 820 (c) 8200
  35. 35.Best estimate of 1198 ÷ 42? (a) 300 (b) 3000 (c) 30
  36. 36.√75 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.6 (d) 8.7
  37. 37.√66 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.0 (d) 8.1
  38. 38.Best estimate of 3515 ÷ 46? (a) 70 (b) 700 (c) 7000
  39. 39.√56 to 1 decimal place? (a) 7.5 (b) 7.7 (c) 7.8 (d) 7.6
  40. 40.Best estimate of 2595 ÷ 63? (a) 4300 (b) 43 (c) 430

Answer key

  1. 28
  2. 4.6
  3. 4.5
  4. 9.2
  5. 96
  6. 8.1
  7. 46
  8. 9.7
  9. 31
  10. 5.4
  11. 9.1
  12. 47
  13. 82
  14. 25
  15. 19
  16. 7.1
  17. 15
  18. 59
  19. 6.3
  20. 18
  21. 15
  22. 9.4
  23. 5.5
  24. 36
  25. 9.1
  26. 7.4
  27. 7.9
  28. 92
  29. 17
  30. 103
  31. 64
  32. 6.6
  33. 25
  34. 82
  35. 30
  36. 8.7
  37. 8.1
  38. 70
  39. 7.5
  40. 43

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