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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 441 · 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.√65 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 8.2 (d) 7.9
  2. 2.Best estimate of 4630 ÷ 87? (a) 5100 (b) 510 (c) 51
  3. 3.Best estimate of 5434 ÷ 59? (a) 91 (b) 910 (c) 9100
  4. 4.√20 to 1 decimal place? (a) 4.4 (b) 4.3 (c) 4.5 (d) 4.2
  5. 5.√92 to 1 decimal place? (a) 9.6 (b) 9.9 (c) 9.7 (d) 9.8
  6. 6.√89 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.3 (d) 9.2
  7. 7.√40 to 1 decimal place? (a) 6.6 (b) 6.5 (c) 6.3 (d) 6.4
  8. 8.√37 to 1 decimal place? (a) 5.9 (b) 5.8 (c) 6.1 (d) 6.0
  9. 9.Best estimate of 1545 ÷ 78? (a) 19 (b) 1900 (c) 190
  10. 10.Best estimate of 1629 ÷ 29? (a) 540 (b) 5400 (c) 54
  11. 11.Best estimate of 4630 ÷ 72? (a) 6600 (b) 660 (c) 66
  12. 12.√94 to 1 decimal place? (a) 9.4 (b) 9.7 (c) 9.6 (d) 9.5
  13. 13.Best estimate of 524 ÷ 24? (a) 260 (b) 26 (c) 2600
  14. 14.Best estimate of 7988 ÷ 86? (a) 89 (b) 890 (c) 8900
  15. 15.√96 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.7 (d) 9.8
  16. 16.Best estimate of 7601 ÷ 83? (a) 95 (b) 950 (c) 9500
  17. 17.Best estimate of 7820 ÷ 84? (a) 9800 (b) 980 (c) 98
  18. 18.√79 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 9.2 (d) 9.1
  19. 19.Best estimate of 6857 ÷ 72? (a) 980 (b) 98 (c) 9800
  20. 20.√27 to 1 decimal place? (a) 5.3 (b) 5.4 (c) 5.1 (d) 5.2
  21. 21.Best estimate of 1354 ÷ 41? (a) 3400 (b) 340 (c) 34
  22. 22.√74 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.5 (d) 8.6
  23. 23.Best estimate of 2253 ÷ 28? (a) 75 (b) 750 (c) 7500
  24. 24.√29 to 1 decimal place? (a) 5.1 (b) 5.3 (c) 5.4 (d) 5.2
  25. 25.Best estimate of 788 ÷ 34? (a) 2600 (b) 260 (c) 26
  26. 26.Best estimate of 2856 ÷ 62? (a) 4800 (b) 480 (c) 48
  27. 27.Best estimate of 840 ÷ 32? (a) 28 (b) 280 (c) 2800
  28. 28.Best estimate of 841 ÷ 49? (a) 1700 (b) 17 (c) 170
  29. 29.√22 to 1 decimal place? (a) 4.9 (b) 4.7 (c) 4.8 (d) 5.0
  30. 30.√58 to 1 decimal place? (a) 7.9 (b) 7.7 (c) 7.8 (d) 7.6
  31. 31.√55 to 1 decimal place? (a) 7.2 (b) 7.5 (c) 7.3 (d) 7.4
  32. 32.Best estimate of 2646 ÷ 83? (a) 33 (b) 3300 (c) 330
  33. 33.Best estimate of 521 ÷ 29? (a) 1700 (b) 17 (c) 170
  34. 34.√98 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 10.0 (d) 9.7
  35. 35.√44 to 1 decimal place? (a) 6.3 (b) 6.6 (c) 6.5 (d) 6.4
  36. 36.Best estimate of 5080 ÷ 67? (a) 73 (b) 7300 (c) 730
  37. 37.Best estimate of 2016 ÷ 26? (a) 670 (b) 6700 (c) 67
  38. 38.Best estimate of 2487 ÷ 71? (a) 360 (b) 3600 (c) 36
  39. 39.√53 to 1 decimal place? (a) 7.5 (b) 7.4 (c) 7.2 (d) 7.3
  40. 40.Best estimate of 1853 ÷ 66? (a) 26 (b) 260 (c) 2600

Answer key

  1. 8.1
  2. 51
  3. 91
  4. 4.5
  5. 9.6
  6. 9.4
  7. 6.3
  8. 6.1
  9. 19
  10. 54
  11. 66
  12. 9.7
  13. 26
  14. 89
  15. 9.8
  16. 95
  17. 98
  18. 8.9
  19. 98
  20. 5.2
  21. 34
  22. 8.6
  23. 75
  24. 5.4
  25. 26
  26. 48
  27. 28
  28. 17
  29. 4.7
  30. 7.6
  31. 7.4
  32. 33
  33. 17
  34. 9.9
  35. 6.6
  36. 73
  37. 67
  38. 36
  39. 7.3
  40. 26

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