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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 793 · 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 3436 ÷ 86? (a) 380 (b) 3800 (c) 38
  2. 2.Best estimate of 2648 ÷ 73? (a) 380 (b) 38 (c) 3800
  3. 3.√26 to 1 decimal place? (a) 5.3 (b) 5.0 (c) 5.2 (d) 5.1
  4. 4.√23 to 1 decimal place? (a) 4.9 (b) 4.8 (c) 5.0 (d) 4.7
  5. 5.Best estimate of 1054 ÷ 22? (a) 5300 (b) 53 (c) 530
  6. 6.Best estimate of 1217 ÷ 21? (a) 61 (b) 610 (c) 6100
  7. 7.Best estimate of 6545 ÷ 72? (a) 940 (b) 9400 (c) 94
  8. 8.Best estimate of 1590 ÷ 29? (a) 53 (b) 5300 (c) 530
  9. 9.√94 to 1 decimal place? (a) 9.7 (b) 10.0 (c) 9.8 (d) 9.9
  10. 10.√83 to 1 decimal place? (a) 8.9 (b) 9.2 (c) 9.1 (d) 9.0
  11. 11.Best estimate of 2006 ÷ 44? (a) 500 (b) 5000 (c) 50
  12. 12.Best estimate of 1628 ÷ 82? (a) 200 (b) 2000 (c) 20
  13. 13.Best estimate of 5332 ÷ 71? (a) 7600 (b) 76 (c) 760
  14. 14.Best estimate of 2476 ÷ 32? (a) 830 (b) 83 (c) 8300
  15. 15.√59 to 1 decimal place? (a) 7.7 (b) 8.0 (c) 7.9 (d) 7.8
  16. 16.Best estimate of 3020 ÷ 68? (a) 43 (b) 4300 (c) 430
  17. 17.√21 to 1 decimal place? (a) 4.7 (b) 4.8 (c) 4.6 (d) 4.9
  18. 18.Best estimate of 1517 ÷ 46? (a) 300 (b) 30 (c) 3000
  19. 19.√65 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.0 (d) 8.1
  20. 20.Best estimate of 5157 ÷ 58? (a) 860 (b) 8600 (c) 86
  21. 21.√51 to 1 decimal place? (a) 7.4 (b) 7.1 (c) 7.2 (d) 7.3
  22. 22.Best estimate of 846 ÷ 48? (a) 17 (b) 1700 (c) 170
  23. 23.Best estimate of 1233 ÷ 34? (a) 410 (b) 4100 (c) 41
  24. 24.Best estimate of 1595 ÷ 32? (a) 530 (b) 53 (c) 5300
  25. 25.Best estimate of 6536 ÷ 86? (a) 73 (b) 730 (c) 7300
  26. 26.Best estimate of 2251 ÷ 26? (a) 750 (b) 7500 (c) 75
  27. 27.Best estimate of 1663 ÷ 28? (a) 550 (b) 55 (c) 5500
  28. 28.√58 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.5 (d) 7.3
  29. 29.√52 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 7.3 (d) 7.0
  30. 30.√72 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.4 (d) 8.3
  31. 31.Best estimate of 5748 ÷ 81? (a) 7200 (b) 72 (c) 720
  32. 32.Best estimate of 629 ÷ 39? (a) 1600 (b) 16 (c) 160
  33. 33.Best estimate of 1890 ÷ 66? (a) 2700 (b) 270 (c) 27
  34. 34.√30 to 1 decimal place? (a) 5.5 (b) 5.8 (c) 5.6 (d) 5.7
  35. 35.√61 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 7.9 (d) 7.8
  36. 36.√90 to 1 decimal place? (a) 9.4 (b) 9.7 (c) 9.6 (d) 9.5
  37. 37.Best estimate of 1522 ÷ 62? (a) 25 (b) 250 (c) 2500
  38. 38.Best estimate of 2734 ÷ 47? (a) 5500 (b) 550 (c) 55
  39. 39.√71 to 1 decimal place? (a) 8.3 (b) 8.5 (c) 8.4 (d) 8.2
  40. 40.Best estimate of 903 ÷ 26? (a) 30 (b) 3000 (c) 300

Answer key

  1. 38
  2. 38
  3. 5.1
  4. 4.8
  5. 53
  6. 61
  7. 94
  8. 53
  9. 9.7
  10. 9.1
  11. 50
  12. 20
  13. 76
  14. 83
  15. 7.7
  16. 43
  17. 4.6
  18. 30
  19. 8.1
  20. 86
  21. 7.1
  22. 17
  23. 41
  24. 53
  25. 73
  26. 75
  27. 55
  28. 7.6
  29. 7.2
  30. 8.5
  31. 72
  32. 16
  33. 27
  34. 5.5
  35. 7.8
  36. 9.5
  37. 25
  38. 55
  39. 8.4
  40. 30

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