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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 616 · 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 1977 ÷ 54? (a) 4000 (b) 400 (c) 40
  2. 2.√43 to 1 decimal place? (a) 6.4 (b) 6.6 (c) 6.5 (d) 6.7
  3. 3.Best estimate of 2760 ÷ 31? (a) 9200 (b) 920 (c) 92
  4. 4.Best estimate of 1201 ÷ 26? (a) 400 (b) 40 (c) 4000
  5. 5.√46 to 1 decimal place? (a) 6.6 (b) 6.5 (c) 6.7 (d) 6.8
  6. 6.√65 to 1 decimal place? (a) 7.9 (b) 8.1 (c) 8.0 (d) 7.8
  7. 7.√79 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 9.0 (d) 9.1
  8. 8.√38 to 1 decimal place? (a) 6.3 (b) 6.0 (c) 6.2 (d) 6.1
  9. 9.√63 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 8.2 (d) 7.9
  10. 10.√32 to 1 decimal place? (a) 5.9 (b) 5.7 (c) 5.8 (d) 5.6
  11. 11.√30 to 1 decimal place? (a) 5.4 (b) 5.7 (c) 5.6 (d) 5.5
  12. 12.Best estimate of 3653 ÷ 44? (a) 910 (b) 9100 (c) 91
  13. 13.Best estimate of 6892 ÷ 72? (a) 98 (b) 9800 (c) 980
  14. 14.Best estimate of 3580 ÷ 52? (a) 720 (b) 7200 (c) 72
  15. 15.Best estimate of 5768 ÷ 76? (a) 72 (b) 720 (c) 7200
  16. 16.Best estimate of 560 ÷ 29? (a) 190 (b) 1900 (c) 19
  17. 17.Best estimate of 4181 ÷ 56? (a) 700 (b) 70 (c) 7000
  18. 18.Best estimate of 3463 ÷ 79? (a) 4300 (b) 430 (c) 43
  19. 19.Best estimate of 3494 ÷ 47? (a) 70 (b) 700 (c) 7000
  20. 20.√21 to 1 decimal place? (a) 4.5 (b) 4.8 (c) 4.7 (d) 4.6
  21. 21.Best estimate of 303 ÷ 24? (a) 15 (b) 1500 (c) 150
  22. 22.√40 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.5 (d) 6.2
  23. 23.Best estimate of 5982 ÷ 72? (a) 8500 (b) 850 (c) 85
  24. 24.√37 to 1 decimal place? (a) 5.8 (b) 6.1 (c) 5.9 (d) 6.0
  25. 25.√89 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.3 (d) 9.2
  26. 26.√67 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.1 (d) 8.0
  27. 27.Best estimate of 1991 ÷ 53? (a) 4000 (b) 400 (c) 40
  28. 28.Best estimate of 3072 ÷ 63? (a) 510 (b) 51 (c) 5100
  29. 29.√96 to 1 decimal place? (a) 10.1 (b) 9.8 (c) 9.9 (d) 10.0
  30. 30.Best estimate of 1201 ÷ 36? (a) 300 (b) 30 (c) 3000
  31. 31.Best estimate of 2011 ÷ 36? (a) 5000 (b) 50 (c) 500
  32. 32.Best estimate of 1279 ÷ 36? (a) 3200 (b) 320 (c) 32
  33. 33.√34 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.7 (d) 5.8
  34. 34.√28 to 1 decimal place? (a) 5.4 (b) 5.5 (c) 5.6 (d) 5.3
  35. 35.Best estimate of 2482 ÷ 51? (a) 5000 (b) 500 (c) 50
  36. 36.Best estimate of 4197 ÷ 51? (a) 84 (b) 840 (c) 8400
  37. 37.Best estimate of 4908 ÷ 58? (a) 820 (b) 82 (c) 8200
  38. 38.√82 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.4 (d) 9.1
  39. 39.Best estimate of 1764 ÷ 67? (a) 25 (b) 250 (c) 2500
  40. 40.Best estimate of 6577 ÷ 86? (a) 7300 (b) 73 (c) 730

Answer key

  1. 40
  2. 6.6
  3. 92
  4. 40
  5. 6.8
  6. 8.1
  7. 8.9
  8. 6.2
  9. 7.9
  10. 5.7
  11. 5.5
  12. 91
  13. 98
  14. 72
  15. 72
  16. 19
  17. 70
  18. 43
  19. 70
  20. 4.6
  21. 15
  22. 6.3
  23. 85
  24. 6.1
  25. 9.4
  26. 8.2
  27. 40
  28. 51
  29. 9.8
  30. 30
  31. 50
  32. 32
  33. 5.8
  34. 5.3
  35. 50
  36. 84
  37. 82
  38. 9.1
  39. 25
  40. 73

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