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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 803 · 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.√37 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 5.8 (d) 6.1
  2. 2.√29 to 1 decimal place? (a) 5.4 (b) 5.6 (c) 5.5 (d) 5.7
  3. 3.Best estimate of 2575 ÷ 78? (a) 320 (b) 3200 (c) 32
  4. 4.√50 to 1 decimal place? (a) 7.3 (b) 7.1 (c) 7.4 (d) 7.2
  5. 5.Best estimate of 5901 ÷ 64? (a) 98 (b) 980 (c) 9800
  6. 6.Best estimate of 4361 ÷ 69? (a) 620 (b) 6200 (c) 62
  7. 7.Best estimate of 6665 ÷ 79? (a) 8300 (b) 83 (c) 830
  8. 8.Best estimate of 642 ÷ 43? (a) 160 (b) 1600 (c) 16
  9. 9.√96 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 10.0 (d) 9.9
  10. 10.√79 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 9.2 (d) 8.9
  11. 11.√23 to 1 decimal place? (a) 4.8 (b) 5.1 (c) 5.0 (d) 4.9
  12. 12.Best estimate of 3428 ÷ 46? (a) 69 (b) 690 (c) 6900
  13. 13.√90 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.4 (d) 9.5
  14. 14.√30 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.5 (d) 5.8
  15. 15.√61 to 1 decimal place? (a) 7.9 (b) 7.8 (c) 8.0 (d) 7.7
  16. 16.Best estimate of 4303 ÷ 72? (a) 6100 (b) 610 (c) 61
  17. 17.Best estimate of 7360 ÷ 81? (a) 92 (b) 920 (c) 9200
  18. 18.√72 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.5 (d) 8.6
  19. 19.Best estimate of 2164 ÷ 26? (a) 720 (b) 7200 (c) 72
  20. 20.√20 to 1 decimal place? (a) 4.4 (b) 4.3 (c) 4.5 (d) 4.2
  21. 21.Best estimate of 1486 ÷ 79? (a) 19 (b) 190 (c) 1900
  22. 22.Best estimate of 2453 ÷ 76? (a) 31 (b) 310 (c) 3100
  23. 23.Best estimate of 1657 ÷ 32? (a) 550 (b) 5500 (c) 55
  24. 24.√78 to 1 decimal place? (a) 8.9 (b) 8.6 (c) 8.7 (d) 8.8
  25. 25.√65 to 1 decimal place? (a) 7.9 (b) 8.1 (c) 8.0 (d) 8.2
  26. 26.√46 to 1 decimal place? (a) 6.9 (b) 6.6 (c) 6.7 (d) 6.8
  27. 27.√67 to 1 decimal place? (a) 8.3 (b) 8.1 (c) 8.2 (d) 8.4
  28. 28.Best estimate of 1418 ÷ 26? (a) 4700 (b) 47 (c) 470
  29. 29.√34 to 1 decimal place? (a) 5.8 (b) 5.7 (c) 5.6 (d) 5.5
  30. 30.Best estimate of 1350 ÷ 42? (a) 3400 (b) 34 (c) 340
  31. 31.√22 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.4 (d) 4.5
  32. 32.Best estimate of 1383 ÷ 26? (a) 460 (b) 4600 (c) 46
  33. 33.√26 to 1 decimal place? (a) 5.2 (b) 5.1 (c) 5.3 (d) 5.4
  34. 34.√88 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.6 (d) 9.5
  35. 35.Best estimate of 3707 ÷ 47? (a) 740 (b) 74 (c) 7400
  36. 36.Best estimate of 5136 ÷ 61? (a) 8600 (b) 860 (c) 86
  37. 37.Best estimate of 4934 ÷ 82? (a) 6200 (b) 62 (c) 620
  38. 38.Best estimate of 851 ÷ 21? (a) 4300 (b) 43 (c) 430
  39. 39.Best estimate of 845 ÷ 26? (a) 280 (b) 2800 (c) 28
  40. 40.Best estimate of 2131 ÷ 28? (a) 7100 (b) 71 (c) 710

Answer key

  1. 6.1
  2. 5.4
  3. 32
  4. 7.1
  5. 98
  6. 62
  7. 83
  8. 16
  9. 9.8
  10. 8.9
  11. 4.8
  12. 69
  13. 9.5
  14. 5.5
  15. 7.8
  16. 61
  17. 92
  18. 8.5
  19. 72
  20. 4.5
  21. 19
  22. 31
  23. 55
  24. 8.8
  25. 8.1
  26. 6.8
  27. 8.2
  28. 47
  29. 5.8
  30. 34
  31. 4.7
  32. 46
  33. 5.1
  34. 9.4
  35. 74
  36. 86
  37. 62
  38. 43
  39. 28
  40. 71

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