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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 901 · 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 1447 ÷ 64? (a) 240 (b) 2400 (c) 24
  2. 2.Best estimate of 4630 ÷ 67? (a) 6600 (b) 660 (c) 66
  3. 3.√62 to 1 decimal place? (a) 8.0 (b) 8.2 (c) 7.9 (d) 8.1
  4. 4.Best estimate of 3351 ÷ 37? (a) 8400 (b) 840 (c) 84
  5. 5.√29 to 1 decimal place? (a) 5.6 (b) 5.4 (c) 5.7 (d) 5.5
  6. 6.Best estimate of 1084 ÷ 66? (a) 15 (b) 150 (c) 1500
  7. 7.√88 to 1 decimal place? (a) 9.6 (b) 9.3 (c) 9.4 (d) 9.5
  8. 8.√70 to 1 decimal place? (a) 8.2 (b) 8.4 (c) 8.5 (d) 8.3
  9. 9.Best estimate of 589 ÷ 31? (a) 2000 (b) 20 (c) 200
  10. 10.√50 to 1 decimal place? (a) 7.0 (b) 7.2 (c) 7.1 (d) 6.9
  11. 11.√55 to 1 decimal place? (a) 7.4 (b) 7.1 (c) 7.3 (d) 7.2
  12. 12.√52 to 1 decimal place? (a) 7.2 (b) 7.4 (c) 7.1 (d) 7.3
  13. 13.Best estimate of 3548 ÷ 82? (a) 44 (b) 440 (c) 4400
  14. 14.Best estimate of 7688 ÷ 83? (a) 9600 (b) 96 (c) 960
  15. 15.Best estimate of 776 ÷ 39? (a) 190 (b) 19 (c) 1900
  16. 16.Best estimate of 2107 ÷ 72? (a) 300 (b) 3000 (c) 30
  17. 17.Best estimate of 4467 ÷ 53? (a) 8900 (b) 890 (c) 89
  18. 18.√85 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.4 (d) 9.1
  19. 19.Best estimate of 3780 ÷ 41? (a) 9500 (b) 950 (c) 95
  20. 20.Best estimate of 4732 ÷ 74? (a) 68 (b) 680 (c) 6800
  21. 21.√32 to 1 decimal place? (a) 5.8 (b) 5.9 (c) 5.7 (d) 5.6
  22. 22.Best estimate of 1613 ÷ 21? (a) 8100 (b) 81 (c) 810
  23. 23.√28 to 1 decimal place? (a) 5.5 (b) 5.4 (c) 5.2 (d) 5.3
  24. 24.√80 to 1 decimal place? (a) 9.0 (b) 9.2 (c) 9.1 (d) 8.9
  25. 25.√96 to 1 decimal place? (a) 10.0 (b) 9.9 (c) 9.8 (d) 9.7
  26. 26.Best estimate of 5735 ÷ 63? (a) 96 (b) 9600 (c) 960
  27. 27.√30 to 1 decimal place? (a) 5.5 (b) 5.3 (c) 5.6 (d) 5.4
  28. 28.Best estimate of 5272 ÷ 81? (a) 660 (b) 66 (c) 6600
  29. 29.Best estimate of 6370 ÷ 83? (a) 800 (b) 80 (c) 8000
  30. 30.√71 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.7 (d) 8.4
  31. 31.Best estimate of 2996 ÷ 33? (a) 10000 (b) 1000 (c) 100
  32. 32.Best estimate of 3643 ÷ 86? (a) 4000 (b) 40 (c) 400
  33. 33.Best estimate of 1844 ÷ 73? (a) 2600 (b) 260 (c) 26
  34. 34.√58 to 1 decimal place? (a) 7.4 (b) 7.6 (c) 7.7 (d) 7.5
  35. 35.Best estimate of 4484 ÷ 77? (a) 56 (b) 560 (c) 5600
  36. 36.Best estimate of 2162 ÷ 72? (a) 3100 (b) 31 (c) 310
  37. 37.√53 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 7.3 (d) 7.0
  38. 38.√38 to 1 decimal place? (a) 6.4 (b) 6.2 (c) 6.1 (d) 6.3
  39. 39.√34 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 5.7 (d) 5.8
  40. 40.Best estimate of 6183 ÷ 66? (a) 880 (b) 8800 (c) 88

Answer key

  1. 24
  2. 66
  3. 7.9
  4. 84
  5. 5.4
  6. 15
  7. 9.4
  8. 8.4
  9. 20
  10. 7.1
  11. 7.4
  12. 7.2
  13. 44
  14. 96
  15. 19
  16. 30
  17. 89
  18. 9.2
  19. 95
  20. 68
  21. 5.7
  22. 81
  23. 5.3
  24. 8.9
  25. 9.8
  26. 96
  27. 5.5
  28. 66
  29. 80
  30. 8.4
  31. 100
  32. 40
  33. 26
  34. 7.6
  35. 56
  36. 31
  37. 7.3
  38. 6.2
  39. 5.8
  40. 88

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