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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 540 · 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 1847 ÷ 28? (a) 620 (b) 6200 (c) 62
  2. 2.√96 to 1 decimal place? (a) 10.0 (b) 9.8 (c) 9.9 (d) 10.1
  3. 3.√42 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 6.6 (d) 6.5
  4. 4.√51 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.0 (d) 7.3
  5. 5.Best estimate of 710 ÷ 23? (a) 3600 (b) 36 (c) 360
  6. 6.√94 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 9.7 (d) 9.6
  7. 7.Best estimate of 1585 ÷ 59? (a) 2600 (b) 260 (c) 26
  8. 8.√34 to 1 decimal place? (a) 5.8 (b) 5.5 (c) 5.6 (d) 5.7
  9. 9.Best estimate of 1841 ÷ 46? (a) 37 (b) 3700 (c) 370
  10. 10.Best estimate of 603 ÷ 34? (a) 20 (b) 2000 (c) 200
  11. 11.√65 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 8.1 (d) 7.8
  12. 12.Best estimate of 284 ÷ 22? (a) 140 (b) 14 (c) 1400
  13. 13.Best estimate of 5149 ÷ 72? (a) 74 (b) 7400 (c) 740
  14. 14.Best estimate of 434 ÷ 31? (a) 1400 (b) 140 (c) 14
  15. 15.Best estimate of 719 ÷ 42? (a) 1800 (b) 18 (c) 180
  16. 16.√50 to 1 decimal place? (a) 7.2 (b) 7.0 (c) 7.1 (d) 6.9
  17. 17.Best estimate of 5501 ÷ 66? (a) 790 (b) 79 (c) 7900
  18. 18.√89 to 1 decimal place? (a) 9.5 (b) 9.2 (c) 9.4 (d) 9.3
  19. 19.Best estimate of 4933 ÷ 82? (a) 62 (b) 620 (c) 6200
  20. 20.√74 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.9 (d) 8.6
  21. 21.Best estimate of 1954 ÷ 31? (a) 65 (b) 6500 (c) 650
  22. 22.Best estimate of 566 ÷ 31? (a) 190 (b) 19 (c) 1900
  23. 23.Best estimate of 3535 ÷ 53? (a) 7100 (b) 71 (c) 710
  24. 24.√77 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.9 (d) 9.0
  25. 25.Best estimate of 2506 ÷ 58? (a) 420 (b) 42 (c) 4200
  26. 26.√23 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 4.9 (d) 4.6
  27. 27.Best estimate of 1165 ÷ 27? (a) 390 (b) 3900 (c) 39
  28. 28.√32 to 1 decimal place? (a) 5.8 (b) 5.9 (c) 6.0 (d) 5.7
  29. 29.Best estimate of 2519 ÷ 46? (a) 5000 (b) 50 (c) 500
  30. 30.√67 to 1 decimal place? (a) 8.0 (b) 8.2 (c) 8.1 (d) 8.3
  31. 31.Best estimate of 2419 ÷ 81? (a) 3000 (b) 300 (c) 30
  32. 32.Best estimate of 1289 ÷ 43? (a) 32 (b) 3200 (c) 320
  33. 33.√20 to 1 decimal place? (a) 4.3 (b) 4.4 (c) 4.5 (d) 4.2
  34. 34.Best estimate of 673 ÷ 42? (a) 17 (b) 170 (c) 1700
  35. 35.√22 to 1 decimal place? (a) 4.8 (b) 4.6 (c) 4.9 (d) 4.7
  36. 36.√26 to 1 decimal place? (a) 5.0 (b) 5.1 (c) 4.9 (d) 4.8
  37. 37.√37 to 1 decimal place? (a) 6.1 (b) 6.0 (c) 6.3 (d) 6.2
  38. 38.√40 to 1 decimal place? (a) 6.4 (b) 6.2 (c) 6.1 (d) 6.3
  39. 39.√38 to 1 decimal place? (a) 6.0 (b) 6.2 (c) 6.3 (d) 6.1
  40. 40.Best estimate of 7833 ÷ 82? (a) 9800 (b) 98 (c) 980

Answer key

  1. 62
  2. 9.8
  3. 6.5
  4. 7.1
  5. 36
  6. 9.7
  7. 26
  8. 5.8
  9. 37
  10. 20
  11. 8.1
  12. 14
  13. 74
  14. 14
  15. 18
  16. 7.1
  17. 79
  18. 9.4
  19. 62
  20. 8.6
  21. 65
  22. 19
  23. 71
  24. 8.8
  25. 42
  26. 4.8
  27. 39
  28. 5.7
  29. 50
  30. 8.2
  31. 30
  32. 32
  33. 4.5
  34. 17
  35. 4.7
  36. 5.1
  37. 6.1
  38. 6.3
  39. 6.2
  40. 98

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