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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 492 · 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 4092 ÷ 86? (a) 450 (b) 4500 (c) 45
  2. 2.√27 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.2 (d) 5.1
  3. 3.Best estimate of 3316 ÷ 77? (a) 4100 (b) 410 (c) 41
  4. 4.√21 to 1 decimal place? (a) 4.7 (b) 4.6 (c) 4.5 (d) 4.4
  5. 5.√65 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 8.4 (d) 8.3
  6. 6.Best estimate of 1969 ÷ 62? (a) 3300 (b) 330 (c) 33
  7. 7.Best estimate of 1516 ÷ 54? (a) 3000 (b) 300 (c) 30
  8. 8.Best estimate of 4831 ÷ 74? (a) 6900 (b) 690 (c) 69
  9. 9.Best estimate of 6399 ÷ 82? (a) 800 (b) 8000 (c) 80
  10. 10.Best estimate of 425 ÷ 34? (a) 1400 (b) 140 (c) 14
  11. 11.Best estimate of 2453 ÷ 72? (a) 35 (b) 350 (c) 3500
  12. 12.Best estimate of 593 ÷ 31? (a) 200 (b) 20 (c) 2000
  13. 13.√69 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.3 (d) 8.4
  14. 14.Best estimate of 2956 ÷ 83? (a) 370 (b) 3700 (c) 37
  15. 15.Best estimate of 784 ÷ 47? (a) 16 (b) 1600 (c) 160
  16. 16.Best estimate of 5984 ÷ 77? (a) 75 (b) 750 (c) 7500
  17. 17.√92 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.8 (d) 9.5
  18. 18.Best estimate of 2652 ÷ 72? (a) 38 (b) 380 (c) 3800
  19. 19.√55 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.7 (d) 7.4
  20. 20.Best estimate of 1092 ÷ 21? (a) 55 (b) 550 (c) 5500
  21. 21.Best estimate of 1853 ÷ 32? (a) 6200 (b) 62 (c) 620
  22. 22.√41 to 1 decimal place? (a) 6.4 (b) 6.2 (c) 6.5 (d) 6.3
  23. 23.√37 to 1 decimal place? (a) 6.1 (b) 6.0 (c) 5.9 (d) 6.2
  24. 24.Best estimate of 2692 ÷ 36? (a) 6700 (b) 67 (c) 670
  25. 25.√82 to 1 decimal place? (a) 9.3 (b) 9.1 (c) 9.2 (d) 9.0
  26. 26.√94 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 9.6 (d) 9.7
  27. 27.√66 to 1 decimal place? (a) 7.9 (b) 7.8 (c) 8.1 (d) 8.0
  28. 28.Best estimate of 1474 ÷ 26? (a) 49 (b) 490 (c) 4900
  29. 29.√35 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 6.1 (d) 6.2
  30. 30.√87 to 1 decimal place? (a) 9.3 (b) 9.5 (c) 9.4 (d) 9.2
  31. 31.Best estimate of 919 ÷ 27? (a) 31 (b) 310 (c) 3100
  32. 32.Best estimate of 977 ÷ 53? (a) 200 (b) 2000 (c) 20
  33. 33.√45 to 1 decimal place? (a) 7.0 (b) 6.7 (c) 6.8 (d) 6.9
  34. 34.Best estimate of 1952 ÷ 28? (a) 6500 (b) 650 (c) 65
  35. 35.Best estimate of 1683 ÷ 84? (a) 210 (b) 2100 (c) 21
  36. 36.√59 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.9 (d) 8.0
  37. 37.Best estimate of 2981 ÷ 53? (a) 60 (b) 6000 (c) 600
  38. 38.Best estimate of 495 ÷ 27? (a) 170 (b) 1700 (c) 17
  39. 39.Best estimate of 3042 ÷ 42? (a) 76 (b) 760 (c) 7600
  40. 40.Best estimate of 3025 ÷ 54? (a) 61 (b) 610 (c) 6100

Answer key

  1. 45
  2. 5.2
  3. 41
  4. 4.6
  5. 8.1
  6. 33
  7. 30
  8. 69
  9. 80
  10. 14
  11. 35
  12. 20
  13. 8.3
  14. 37
  15. 16
  16. 75
  17. 9.6
  18. 38
  19. 7.4
  20. 55
  21. 62
  22. 6.4
  23. 6.1
  24. 67
  25. 9.1
  26. 9.7
  27. 8.1
  28. 49
  29. 5.9
  30. 9.3
  31. 31
  32. 20
  33. 6.7
  34. 65
  35. 21
  36. 7.7
  37. 60
  38. 17
  39. 76
  40. 61

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