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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 569 · 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.√32 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.4 (d) 5.7
  2. 2.Best estimate of 2205 ÷ 47? (a) 4400 (b) 44 (c) 440
  3. 3.√83 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 9.1 (d) 9.0
  4. 4.√74 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.4 (d) 8.7
  5. 5.Best estimate of 5262 ÷ 78? (a) 660 (b) 6600 (c) 66
  6. 6.√65 to 1 decimal place? (a) 7.8 (b) 8.1 (c) 7.9 (d) 8.0
  7. 7.Best estimate of 4772 ÷ 62? (a) 8000 (b) 800 (c) 80
  8. 8.Best estimate of 4670 ÷ 56? (a) 78 (b) 7800 (c) 780
  9. 9.Best estimate of 1520 ÷ 72? (a) 2200 (b) 22 (c) 220
  10. 10.Best estimate of 2589 ÷ 48? (a) 52 (b) 520 (c) 5200
  11. 11.√26 to 1 decimal place? (a) 4.8 (b) 5.0 (c) 5.1 (d) 4.9
  12. 12.Best estimate of 754 ÷ 26? (a) 250 (b) 25 (c) 2500
  13. 13.Best estimate of 2146 ÷ 32? (a) 7200 (b) 72 (c) 720
  14. 14.Best estimate of 911 ÷ 29? (a) 30 (b) 3000 (c) 300
  15. 15.Best estimate of 6744 ÷ 77? (a) 840 (b) 84 (c) 8400
  16. 16.√76 to 1 decimal place? (a) 8.5 (b) 8.7 (c) 8.6 (d) 8.4
  17. 17.Best estimate of 798 ÷ 26? (a) 270 (b) 2700 (c) 27
  18. 18.Best estimate of 4525 ÷ 56? (a) 7500 (b) 75 (c) 750
  19. 19.Best estimate of 583 ÷ 36? (a) 15 (b) 1500 (c) 150
  20. 20.√80 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 8.6 (d) 8.7
  21. 21.Best estimate of 2567 ÷ 44? (a) 640 (b) 64 (c) 6400
  22. 22.√43 to 1 decimal place? (a) 6.7 (b) 6.9 (c) 6.6 (d) 6.8
  23. 23.Best estimate of 2424 ÷ 26? (a) 810 (b) 81 (c) 8100
  24. 24.Best estimate of 1805 ÷ 22? (a) 9000 (b) 900 (c) 90
  25. 25.√24 to 1 decimal place? (a) 4.6 (b) 4.8 (c) 4.9 (d) 4.7
  26. 26.√47 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 6.6 (d) 6.9
  27. 27.Best estimate of 1775 ÷ 22? (a) 890 (b) 89 (c) 8900
  28. 28.√79 to 1 decimal place? (a) 9.0 (b) 9.2 (c) 9.1 (d) 8.9
  29. 29.Best estimate of 4488 ÷ 51? (a) 9000 (b) 900 (c) 90
  30. 30.Best estimate of 5831 ÷ 63? (a) 970 (b) 9700 (c) 97
  31. 31.Best estimate of 1611 ÷ 33? (a) 54 (b) 540 (c) 5400
  32. 32.Best estimate of 3736 ÷ 46? (a) 750 (b) 75 (c) 7500
  33. 33.√28 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.5 (d) 5.4
  34. 34.√72 to 1 decimal place? (a) 8.4 (b) 8.6 (c) 8.5 (d) 8.7
  35. 35.√71 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.4 (d) 8.1
  36. 36.Best estimate of 4294 ÷ 49? (a) 860 (b) 8600 (c) 86
  37. 37.Best estimate of 300 ÷ 22? (a) 1500 (b) 150 (c) 15
  38. 38.Best estimate of 1178 ÷ 21? (a) 590 (b) 59 (c) 5900
  39. 39.Best estimate of 4032 ÷ 49? (a) 8100 (b) 810 (c) 81
  40. 40.√50 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.0 (d) 7.3

Answer key

  1. 5.7
  2. 44
  3. 9.1
  4. 8.6
  5. 66
  6. 8.1
  7. 80
  8. 78
  9. 22
  10. 52
  11. 5.1
  12. 25
  13. 72
  14. 30
  15. 84
  16. 8.7
  17. 27
  18. 75
  19. 15
  20. 8.9
  21. 64
  22. 6.6
  23. 81
  24. 90
  25. 4.9
  26. 6.9
  27. 89
  28. 8.9
  29. 90
  30. 97
  31. 54
  32. 75
  33. 5.3
  34. 8.5
  35. 8.4
  36. 86
  37. 15
  38. 59
  39. 81
  40. 7.1

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