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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 147 · 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 3215 ÷ 36? (a) 8000 (b) 80 (c) 800
  2. 2.√87 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.3 (d) 9.5
  3. 3.Best estimate of 2785 ÷ 42? (a) 7000 (b) 700 (c) 70
  4. 4.Best estimate of 2522 ÷ 46? (a) 5000 (b) 500 (c) 50
  5. 5.Best estimate of 2551 ÷ 44? (a) 640 (b) 6400 (c) 64
  6. 6.√94 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.5 (d) 9.4
  7. 7.Best estimate of 2866 ÷ 43? (a) 72 (b) 720 (c) 7200
  8. 8.Best estimate of 3546 ÷ 57? (a) 590 (b) 5900 (c) 59
  9. 9.√62 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 7.8 (d) 7.7
  10. 10.√92 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.6 (d) 9.4
  11. 11.√28 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.4 (d) 5.5
  12. 12.Best estimate of 3403 ÷ 78? (a) 43 (b) 4300 (c) 430
  13. 13.Best estimate of 1701 ÷ 43? (a) 4300 (b) 430 (c) 43
  14. 14.√58 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.3 (d) 7.6
  15. 15.Best estimate of 4767 ÷ 54? (a) 950 (b) 9500 (c) 95
  16. 16.√26 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.1 (d) 5.0
  17. 17.Best estimate of 2451 ÷ 37? (a) 61 (b) 610 (c) 6100
  18. 18.Best estimate of 1617 ÷ 23? (a) 81 (b) 8100 (c) 810
  19. 19.Best estimate of 1620 ÷ 82? (a) 20 (b) 200 (c) 2000
  20. 20.Best estimate of 7379 ÷ 89? (a) 8200 (b) 820 (c) 82
  21. 21.√56 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.3 (d) 7.4
  22. 22.√76 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 8.7 (d) 8.8
  23. 23.Best estimate of 2833 ÷ 52? (a) 5700 (b) 570 (c) 57
  24. 24.Best estimate of 1252 ÷ 36? (a) 310 (b) 3100 (c) 31
  25. 25.√78 to 1 decimal place? (a) 9.0 (b) 8.7 (c) 8.8 (d) 8.9
  26. 26.Best estimate of 2059 ÷ 28? (a) 690 (b) 69 (c) 6900
  27. 27.√65 to 1 decimal place? (a) 8.1 (b) 8.3 (c) 8.4 (d) 8.2
  28. 28.√29 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.2 (d) 5.5
  29. 29.√67 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.1 (d) 8.4
  30. 30.√89 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.5 (d) 9.2
  31. 31.Best estimate of 1977 ÷ 22? (a) 9900 (b) 99 (c) 990
  32. 32.Best estimate of 3100 ÷ 86? (a) 3400 (b) 34 (c) 340
  33. 33.Best estimate of 777 ÷ 46? (a) 160 (b) 16 (c) 1600
  34. 34.Best estimate of 3929 ÷ 43? (a) 98 (b) 9800 (c) 980
  35. 35.√55 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.5 (d) 7.4
  36. 36.√51 to 1 decimal place? (a) 7.1 (b) 6.9 (c) 7.0 (d) 6.8
  37. 37.√96 to 1 decimal place? (a) 9.9 (b) 10.1 (c) 9.8 (d) 10.0
  38. 38.√80 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 9.0 (d) 8.7
  39. 39.Best estimate of 1083 ÷ 71? (a) 1500 (b) 15 (c) 150
  40. 40.Best estimate of 3809 ÷ 62? (a) 6300 (b) 63 (c) 630

Answer key

  1. 80
  2. 9.3
  3. 70
  4. 50
  5. 64
  6. 9.7
  7. 72
  8. 59
  9. 7.9
  10. 9.6
  11. 5.3
  12. 43
  13. 43
  14. 7.6
  15. 95
  16. 5.1
  17. 61
  18. 81
  19. 20
  20. 82
  21. 7.5
  22. 8.7
  23. 57
  24. 31
  25. 8.8
  26. 69
  27. 8.1
  28. 5.4
  29. 8.2
  30. 9.4
  31. 99
  32. 34
  33. 16
  34. 98
  35. 7.4
  36. 7.1
  37. 9.8
  38. 8.9
  39. 15
  40. 63

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