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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 812 · 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.√40 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.5 (d) 6.2
  2. 2.Best estimate of 3628 ÷ 46? (a) 730 (b) 73 (c) 7300
  3. 3.Best estimate of 1552 ÷ 86? (a) 170 (b) 1700 (c) 17
  4. 4.Best estimate of 4094 ÷ 59? (a) 6800 (b) 68 (c) 680
  5. 5.Best estimate of 4349 ÷ 66? (a) 62 (b) 620 (c) 6200
  6. 6.Best estimate of 2671 ÷ 59? (a) 4500 (b) 45 (c) 450
  7. 7.Best estimate of 2292 ÷ 29? (a) 7600 (b) 76 (c) 760
  8. 8.Best estimate of 1605 ÷ 82? (a) 200 (b) 20 (c) 2000
  9. 9.√82 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 8.8 (d) 8.9
  10. 10.Best estimate of 2005 ÷ 82? (a) 250 (b) 25 (c) 2500
  11. 11.Best estimate of 4090 ÷ 48? (a) 820 (b) 82 (c) 8200
  12. 12.Best estimate of 1141 ÷ 24? (a) 570 (b) 57 (c) 5700
  13. 13.√53 to 1 decimal place? (a) 7.1 (b) 7.4 (c) 7.3 (d) 7.2
  14. 14.Best estimate of 4430 ÷ 52? (a) 890 (b) 8900 (c) 89
  15. 15.Best estimate of 2845 ÷ 32? (a) 95 (b) 950 (c) 9500
  16. 16.√63 to 1 decimal place? (a) 8.1 (b) 7.9 (c) 8.0 (d) 7.8
  17. 17.Best estimate of 5739 ÷ 84? (a) 720 (b) 7200 (c) 72
  18. 18.Best estimate of 1331 ÷ 88? (a) 15 (b) 1500 (c) 150
  19. 19.√51 to 1 decimal place? (a) 7.0 (b) 7.2 (c) 6.9 (d) 7.1
  20. 20.Best estimate of 770 ÷ 62? (a) 130 (b) 1300 (c) 13
  21. 21.√26 to 1 decimal place? (a) 5.0 (b) 5.2 (c) 4.9 (d) 5.1
  22. 22.√92 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.6 (d) 9.5
  23. 23.√66 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.2 (d) 8.1
  24. 24.√28 to 1 decimal place? (a) 5.3 (b) 5.5 (c) 5.4 (d) 5.2
  25. 25.Best estimate of 1004 ÷ 52? (a) 200 (b) 20 (c) 2000
  26. 26.Best estimate of 4077 ÷ 61? (a) 68 (b) 6800 (c) 680
  27. 27.√56 to 1 decimal place? (a) 7.8 (b) 7.5 (c) 7.6 (d) 7.7
  28. 28.√34 to 1 decimal place? (a) 5.9 (b) 6.1 (c) 5.8 (d) 6.0
  29. 29.Best estimate of 6141 ÷ 86? (a) 68 (b) 6800 (c) 680
  30. 30.Best estimate of 6886 ÷ 89? (a) 77 (b) 7700 (c) 770
  31. 31.Best estimate of 1703 ÷ 59? (a) 280 (b) 2800 (c) 28
  32. 32.Best estimate of 6447 ÷ 76? (a) 8100 (b) 81 (c) 810
  33. 33.Best estimate of 2209 ÷ 58? (a) 3700 (b) 37 (c) 370
  34. 34.Best estimate of 560 ÷ 29? (a) 190 (b) 1900 (c) 19
  35. 35.√85 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.3 (d) 9.0
  36. 36.Best estimate of 1221 ÷ 82? (a) 1500 (b) 15 (c) 150
  37. 37.Best estimate of 2495 ÷ 29? (a) 83 (b) 8300 (c) 830
  38. 38.Best estimate of 392 ÷ 21? (a) 200 (b) 2000 (c) 20
  39. 39.Best estimate of 2203 ÷ 43? (a) 55 (b) 550 (c) 5500
  40. 40.Best estimate of 1119 ÷ 48? (a) 2200 (b) 22 (c) 220

Answer key

  1. 6.3
  2. 73
  3. 17
  4. 68
  5. 62
  6. 45
  7. 76
  8. 20
  9. 9.1
  10. 25
  11. 82
  12. 57
  13. 7.3
  14. 89
  15. 95
  16. 7.9
  17. 72
  18. 15
  19. 7.1
  20. 13
  21. 5.1
  22. 9.6
  23. 8.1
  24. 5.3
  25. 20
  26. 68
  27. 7.5
  28. 5.8
  29. 68
  30. 77
  31. 28
  32. 81
  33. 37
  34. 19
  35. 9.2
  36. 15
  37. 83
  38. 20
  39. 55
  40. 22

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