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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 775 · 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.√67 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 8.2 (d) 7.9
  2. 2.Best estimate of 1016 ÷ 33? (a) 340 (b) 34 (c) 3400
  3. 3.Best estimate of 4932 ÷ 82? (a) 6200 (b) 620 (c) 62
  4. 4.Best estimate of 1733 ÷ 26? (a) 58 (b) 5800 (c) 580
  5. 5.Best estimate of 1542 ÷ 56? (a) 26 (b) 2600 (c) 260
  6. 6.√65 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.1 (d) 7.8
  7. 7.√94 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.9 (d) 9.6
  8. 8.Best estimate of 4736 ÷ 68? (a) 680 (b) 68 (c) 6800
  9. 9.Best estimate of 769 ÷ 62? (a) 13 (b) 130 (c) 1300
  10. 10.√89 to 1 decimal place? (a) 9.1 (b) 9.4 (c) 9.3 (d) 9.2
  11. 11.√58 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.6 (d) 7.7
  12. 12.Best estimate of 1671 ÷ 68? (a) 2400 (b) 240 (c) 24
  13. 13.Best estimate of 2375 ÷ 36? (a) 59 (b) 590 (c) 5900
  14. 14.Best estimate of 3042 ÷ 83? (a) 38 (b) 380 (c) 3800
  15. 15.Best estimate of 1620 ÷ 53? (a) 3200 (b) 32 (c) 320
  16. 16.√78 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 8.7 (d) 9.0
  17. 17.√42 to 1 decimal place? (a) 6.5 (b) 6.3 (c) 6.4 (d) 6.6
  18. 18.Best estimate of 466 ÷ 26? (a) 1600 (b) 16 (c) 160
  19. 19.√66 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.1 (d) 8.4
  20. 20.Best estimate of 1971 ÷ 42? (a) 4900 (b) 490 (c) 49
  21. 21.√23 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.9 (d) 4.8
  22. 22.√40 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.1 (d) 6.4
  23. 23.√37 to 1 decimal place? (a) 5.8 (b) 6.0 (c) 5.9 (d) 6.1
  24. 24.√71 to 1 decimal place? (a) 8.7 (b) 8.5 (c) 8.4 (d) 8.6
  25. 25.√92 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.8 (d) 9.5
  26. 26.Best estimate of 2559 ÷ 34? (a) 85 (b) 8500 (c) 850
  27. 27.Best estimate of 3820 ÷ 66? (a) 5500 (b) 550 (c) 55
  28. 28.Best estimate of 1707 ÷ 83? (a) 21 (b) 2100 (c) 210
  29. 29.√53 to 1 decimal place? (a) 7.2 (b) 7.4 (c) 7.1 (d) 7.3
  30. 30.Best estimate of 2469 ÷ 49? (a) 4900 (b) 49 (c) 490
  31. 31.√69 to 1 decimal place? (a) 8.1 (b) 8.3 (c) 8.2 (d) 8.0
  32. 32.Best estimate of 4108 ÷ 82? (a) 5100 (b) 51 (c) 510
  33. 33.√26 to 1 decimal place? (a) 5.3 (b) 5.2 (c) 5.4 (d) 5.1
  34. 34.√79 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 8.8 (d) 8.9
  35. 35.Best estimate of 4369 ÷ 56? (a) 7300 (b) 73 (c) 730
  36. 36.Best estimate of 2052 ÷ 28? (a) 6800 (b) 680 (c) 68
  37. 37.Best estimate of 3124 ÷ 44? (a) 78 (b) 7800 (c) 780
  38. 38.√86 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.1 (d) 9.2
  39. 39.Best estimate of 7317 ÷ 82? (a) 910 (b) 9100 (c) 91
  40. 40.Best estimate of 3850 ÷ 48? (a) 7700 (b) 770 (c) 77

Answer key

  1. 8.2
  2. 34
  3. 62
  4. 58
  5. 26
  6. 8.1
  7. 9.7
  8. 68
  9. 13
  10. 9.4
  11. 7.6
  12. 24
  13. 59
  14. 38
  15. 32
  16. 8.8
  17. 6.5
  18. 16
  19. 8.1
  20. 49
  21. 4.8
  22. 6.3
  23. 6.1
  24. 8.4
  25. 9.6
  26. 85
  27. 55
  28. 21
  29. 7.3
  30. 49
  31. 8.3
  32. 51
  33. 5.1
  34. 8.9
  35. 73
  36. 68
  37. 78
  38. 9.3
  39. 91
  40. 77

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