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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 273 · 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 2251 ÷ 81? (a) 2800 (b) 280 (c) 28
  2. 2.Best estimate of 2424 ÷ 28? (a) 8100 (b) 810 (c) 81
  3. 3.Best estimate of 2734 ÷ 52? (a) 55 (b) 5500 (c) 550
  4. 4.√94 to 1 decimal place? (a) 9.7 (b) 9.9 (c) 9.6 (d) 9.8
  5. 5.Best estimate of 1079 ÷ 62? (a) 18 (b) 180 (c) 1800
  6. 6.Best estimate of 3434 ÷ 42? (a) 860 (b) 8600 (c) 86
  7. 7.√35 to 1 decimal place? (a) 5.8 (b) 5.9 (c) 5.7 (d) 6.0
  8. 8.√63 to 1 decimal place? (a) 7.7 (b) 8.0 (c) 7.9 (d) 7.8
  9. 9.Best estimate of 2474 ÷ 74? (a) 35 (b) 3500 (c) 350
  10. 10.Best estimate of 2954 ÷ 51? (a) 5900 (b) 590 (c) 59
  11. 11.Best estimate of 1020 ÷ 67? (a) 150 (b) 1500 (c) 15
  12. 12.√26 to 1 decimal place? (a) 5.1 (b) 4.9 (c) 5.0 (d) 5.2
  13. 13.Best estimate of 2026 ÷ 56? (a) 34 (b) 3400 (c) 340
  14. 14.Best estimate of 1133 ÷ 42? (a) 2800 (b) 280 (c) 28
  15. 15.Best estimate of 1098 ÷ 46? (a) 22 (b) 220 (c) 2200
  16. 16.√89 to 1 decimal place? (a) 9.7 (b) 9.5 (c) 9.4 (d) 9.6
  17. 17.Best estimate of 6232 ÷ 73? (a) 890 (b) 89 (c) 8900
  18. 18.√87 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.4 (d) 9.1
  19. 19.Best estimate of 1909 ÷ 31? (a) 6400 (b) 64 (c) 640
  20. 20.√83 to 1 decimal place? (a) 9.3 (b) 9.1 (c) 9.2 (d) 9.0
  21. 21.√61 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.5 (d) 7.6
  22. 22.√55 to 1 decimal place? (a) 7.3 (b) 7.5 (c) 7.2 (d) 7.4
  23. 23.√66 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 8.3 (d) 8.2
  24. 24.Best estimate of 3199 ÷ 51? (a) 6400 (b) 64 (c) 640
  25. 25.Best estimate of 1269 ÷ 29? (a) 42 (b) 420 (c) 4200
  26. 26.Best estimate of 741 ÷ 46? (a) 15 (b) 150 (c) 1500
  27. 27.Best estimate of 6110 ÷ 82? (a) 76 (b) 7600 (c) 760
  28. 28.√24 to 1 decimal place? (a) 5.0 (b) 4.7 (c) 4.9 (d) 4.8
  29. 29.Best estimate of 2065 ÷ 78? (a) 2600 (b) 26 (c) 260
  30. 30.Best estimate of 1849 ÷ 32? (a) 620 (b) 6200 (c) 62
  31. 31.Best estimate of 2083 ÷ 71? (a) 300 (b) 30 (c) 3000
  32. 32.√45 to 1 decimal place? (a) 6.9 (b) 6.6 (c) 6.8 (d) 6.7
  33. 33.Best estimate of 6910 ÷ 79? (a) 860 (b) 86 (c) 8600
  34. 34.Best estimate of 4284 ÷ 46? (a) 8600 (b) 86 (c) 860
  35. 35.Best estimate of 3388 ÷ 36? (a) 850 (b) 8500 (c) 85
  36. 36.Best estimate of 3314 ÷ 38? (a) 830 (b) 8300 (c) 83
  37. 37.Best estimate of 1540 ÷ 21? (a) 77 (b) 770 (c) 7700
  38. 38.√74 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.5 (d) 8.4
  39. 39.√65 to 1 decimal place? (a) 7.8 (b) 8.1 (c) 8.0 (d) 7.9
  40. 40.Best estimate of 1010 ÷ 71? (a) 14 (b) 1400 (c) 140

Answer key

  1. 28
  2. 81
  3. 55
  4. 9.7
  5. 18
  6. 86
  7. 5.9
  8. 7.9
  9. 35
  10. 59
  11. 15
  12. 5.1
  13. 34
  14. 28
  15. 22
  16. 9.4
  17. 89
  18. 9.3
  19. 64
  20. 9.1
  21. 7.8
  22. 7.4
  23. 8.1
  24. 64
  25. 42
  26. 15
  27. 76
  28. 4.9
  29. 26
  30. 62
  31. 30
  32. 6.7
  33. 86
  34. 86
  35. 85
  36. 83
  37. 77
  38. 8.6
  39. 8.1
  40. 14

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