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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 450 · 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 6149 ÷ 66? (a) 88 (b) 880 (c) 8800
  2. 2.√86 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.4 (d) 9.6
  3. 3.√32 to 1 decimal place? (a) 5.7 (b) 5.5 (c) 5.6 (d) 5.4
  4. 4.√58 to 1 decimal place? (a) 7.3 (b) 7.6 (c) 7.4 (d) 7.5
  5. 5.Best estimate of 4134 ÷ 61? (a) 6900 (b) 690 (c) 69
  6. 6.√72 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.5 (d) 8.2
  7. 7.√74 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.5 (d) 8.4
  8. 8.Best estimate of 3103 ÷ 76? (a) 390 (b) 3900 (c) 39
  9. 9.√66 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.4 (d) 8.1
  10. 10.Best estimate of 2342 ÷ 39? (a) 5900 (b) 59 (c) 590
  11. 11.√48 to 1 decimal place? (a) 7.2 (b) 6.9 (c) 7.1 (d) 7.0
  12. 12.√21 to 1 decimal place? (a) 4.7 (b) 4.8 (c) 4.6 (d) 4.9
  13. 13.Best estimate of 2088 ÷ 27? (a) 70 (b) 7000 (c) 700
  14. 14.√61 to 1 decimal place? (a) 8.0 (b) 7.8 (c) 8.1 (d) 7.9
  15. 15.Best estimate of 1783 ÷ 81? (a) 2200 (b) 220 (c) 22
  16. 16.Best estimate of 3960 ÷ 69? (a) 57 (b) 5700 (c) 570
  17. 17.Best estimate of 4398 ÷ 52? (a) 880 (b) 88 (c) 8800
  18. 18.√43 to 1 decimal place? (a) 6.5 (b) 6.4 (c) 6.6 (d) 6.7
  19. 19.Best estimate of 4653 ÷ 82? (a) 5800 (b) 58 (c) 580
  20. 20.√20 to 1 decimal place? (a) 4.7 (b) 4.6 (c) 4.5 (d) 4.8
  21. 21.√28 to 1 decimal place? (a) 5.3 (b) 5.4 (c) 5.2 (d) 5.5
  22. 22.Best estimate of 1613 ÷ 52? (a) 3200 (b) 32 (c) 320
  23. 23.√24 to 1 decimal place? (a) 5.1 (b) 4.9 (c) 5.0 (d) 5.2
  24. 24.√50 to 1 decimal place? (a) 7.1 (b) 6.9 (c) 7.0 (d) 6.8
  25. 25.Best estimate of 5236 ÷ 77? (a) 650 (b) 6500 (c) 65
  26. 26.Best estimate of 2306 ÷ 72? (a) 3300 (b) 330 (c) 33
  27. 27.Best estimate of 3390 ÷ 43? (a) 850 (b) 85 (c) 8500
  28. 28.Best estimate of 1332 ÷ 51? (a) 27 (b) 270 (c) 2700
  29. 29.Best estimate of 1041 ÷ 22? (a) 520 (b) 5200 (c) 52
  30. 30.Best estimate of 7807 ÷ 82? (a) 98 (b) 980 (c) 9800
  31. 31.Best estimate of 1211 ÷ 37? (a) 3000 (b) 30 (c) 300
  32. 32.√46 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 7.1 (d) 7.0
  33. 33.√45 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.8 (d) 6.9
  34. 34.Best estimate of 4669 ÷ 54? (a) 93 (b) 9300 (c) 930
  35. 35.Best estimate of 4167 ÷ 72? (a) 60 (b) 6000 (c) 600
  36. 36.Best estimate of 3596 ÷ 43? (a) 900 (b) 9000 (c) 90
  37. 37.Best estimate of 2382 ÷ 42? (a) 600 (b) 6000 (c) 60
  38. 38.Best estimate of 5505 ÷ 87? (a) 61 (b) 610 (c) 6100
  39. 39.√85 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 9.2 (d) 9.1
  40. 40.Best estimate of 8239 ÷ 89? (a) 920 (b) 9200 (c) 92

Answer key

  1. 88
  2. 9.3
  3. 5.7
  4. 7.6
  5. 69
  6. 8.5
  7. 8.6
  8. 39
  9. 8.1
  10. 59
  11. 6.9
  12. 4.6
  13. 70
  14. 7.8
  15. 22
  16. 57
  17. 88
  18. 6.6
  19. 58
  20. 4.5
  21. 5.3
  22. 32
  23. 4.9
  24. 7.1
  25. 65
  26. 33
  27. 85
  28. 27
  29. 52
  30. 98
  31. 30
  32. 6.8
  33. 6.7
  34. 93
  35. 60
  36. 90
  37. 60
  38. 61
  39. 9.2
  40. 92

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