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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 850 · 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.√90 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.8 (d) 9.7
  2. 2.√53 to 1 decimal place? (a) 7.6 (b) 7.5 (c) 7.4 (d) 7.3
  3. 3.Best estimate of 1011 ÷ 36? (a) 2500 (b) 250 (c) 25
  4. 4.Best estimate of 4029 ÷ 52? (a) 8100 (b) 810 (c) 81
  5. 5.√44 to 1 decimal place? (a) 6.6 (b) 6.3 (c) 6.4 (d) 6.5
  6. 6.√58 to 1 decimal place? (a) 7.5 (b) 7.8 (c) 7.6 (d) 7.7
  7. 7.Best estimate of 1019 ÷ 27? (a) 340 (b) 3400 (c) 34
  8. 8.√92 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.8 (d) 9.7
  9. 9.Best estimate of 1755 ÷ 43? (a) 44 (b) 440 (c) 4400
  10. 10.Best estimate of 5674 ÷ 82? (a) 710 (b) 7100 (c) 71
  11. 11.√76 to 1 decimal place? (a) 8.8 (b) 8.5 (c) 8.6 (d) 8.7
  12. 12.Best estimate of 3426 ÷ 66? (a) 490 (b) 4900 (c) 49
  13. 13.√26 to 1 decimal place? (a) 5.1 (b) 5.3 (c) 5.2 (d) 5.0
  14. 14.√70 to 1 decimal place? (a) 8.1 (b) 8.3 (c) 8.2 (d) 8.4
  15. 15.Best estimate of 3369 ÷ 87? (a) 3700 (b) 370 (c) 37
  16. 16.Best estimate of 3134 ÷ 39? (a) 780 (b) 78 (c) 7800
  17. 17.√98 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 10.1 (d) 10.0
  18. 18.Best estimate of 450 ÷ 22? (a) 230 (b) 23 (c) 2300
  19. 19.√80 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 8.7 (d) 8.8
  20. 20.Best estimate of 1481 ÷ 56? (a) 250 (b) 2500 (c) 25
  21. 21.√84 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 8.9 (d) 9.0
  22. 22.Best estimate of 7158 ÷ 83? (a) 890 (b) 8900 (c) 89
  23. 23.Best estimate of 1012 ÷ 29? (a) 34 (b) 340 (c) 3400
  24. 24.Best estimate of 4466 ÷ 59? (a) 740 (b) 7400 (c) 74
  25. 25.√66 to 1 decimal place? (a) 8.0 (b) 8.2 (c) 7.9 (d) 8.1
  26. 26.√41 to 1 decimal place? (a) 6.6 (b) 6.5 (c) 6.4 (d) 6.7
  27. 27.Best estimate of 729 ÷ 42? (a) 180 (b) 1800 (c) 18
  28. 28.√37 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 5.8 (d) 6.1
  29. 29.Best estimate of 639 ÷ 31? (a) 2100 (b) 210 (c) 21
  30. 30.Best estimate of 937 ÷ 24? (a) 4700 (b) 470 (c) 47
  31. 31.Best estimate of 1404 ÷ 67? (a) 200 (b) 2000 (c) 20
  32. 32.Best estimate of 3979 ÷ 68? (a) 5700 (b) 570 (c) 57
  33. 33.√77 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.6 (d) 8.5
  34. 34.Best estimate of 1057 ÷ 34? (a) 35 (b) 350 (c) 3500
  35. 35.Best estimate of 2428 ÷ 42? (a) 61 (b) 6100 (c) 610
  36. 36.√46 to 1 decimal place? (a) 6.8 (b) 7.1 (c) 7.0 (d) 6.9
  37. 37.√94 to 1 decimal place? (a) 9.7 (b) 9.4 (c) 9.5 (d) 9.6
  38. 38.Best estimate of 4744 ÷ 81? (a) 59 (b) 5900 (c) 590
  39. 39.Best estimate of 2620 ÷ 32? (a) 870 (b) 8700 (c) 87
  40. 40.Best estimate of 1721 ÷ 29? (a) 57 (b) 5700 (c) 570

Answer key

  1. 9.5
  2. 7.3
  3. 25
  4. 81
  5. 6.6
  6. 7.6
  7. 34
  8. 9.6
  9. 44
  10. 71
  11. 8.7
  12. 49
  13. 5.1
  14. 8.4
  15. 37
  16. 78
  17. 9.9
  18. 23
  19. 8.9
  20. 25
  21. 9.2
  22. 89
  23. 34
  24. 74
  25. 8.1
  26. 6.4
  27. 18
  28. 6.1
  29. 21
  30. 47
  31. 20
  32. 57
  33. 8.8
  34. 35
  35. 61
  36. 6.8
  37. 9.7
  38. 59
  39. 87
  40. 57

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