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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 479 · 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 3244 ÷ 76? (a) 4100 (b) 410 (c) 41
  2. 2.Best estimate of 774 ÷ 28? (a) 260 (b) 2600 (c) 26
  3. 3.Best estimate of 2221 ÷ 52? (a) 440 (b) 4400 (c) 44
  4. 4.Best estimate of 2569 ÷ 37? (a) 64 (b) 640 (c) 6400
  5. 5.√62 to 1 decimal place? (a) 7.8 (b) 8.0 (c) 7.9 (d) 7.7
  6. 6.√61 to 1 decimal place? (a) 7.9 (b) 7.6 (c) 7.7 (d) 7.8
  7. 7.Best estimate of 3947 ÷ 73? (a) 5600 (b) 560 (c) 56
  8. 8.√28 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.5 (d) 5.6
  9. 9.√58 to 1 decimal place? (a) 7.5 (b) 7.7 (c) 7.4 (d) 7.6
  10. 10.√98 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.9 (d) 9.6
  11. 11.√96 to 1 decimal place? (a) 10.0 (b) 9.9 (c) 10.1 (d) 9.8
  12. 12.√75 to 1 decimal place? (a) 8.8 (b) 8.6 (c) 8.5 (d) 8.7
  13. 13.Best estimate of 1146 ÷ 87? (a) 130 (b) 13 (c) 1300
  14. 14.Best estimate of 2048 ÷ 42? (a) 510 (b) 51 (c) 5100
  15. 15.√32 to 1 decimal place? (a) 5.4 (b) 5.6 (c) 5.5 (d) 5.7
  16. 16.Best estimate of 1777 ÷ 89? (a) 200 (b) 2000 (c) 20
  17. 17.√21 to 1 decimal place? (a) 4.8 (b) 4.6 (c) 4.9 (d) 4.7
  18. 18.Best estimate of 5793 ÷ 81? (a) 72 (b) 7200 (c) 720
  19. 19.Best estimate of 2239 ÷ 76? (a) 2800 (b) 28 (c) 280
  20. 20.√34 to 1 decimal place? (a) 5.9 (b) 5.7 (c) 5.6 (d) 5.8
  21. 21.√94 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.9 (d) 9.7
  22. 22.Best estimate of 1086 ÷ 82? (a) 14 (b) 140 (c) 1400
  23. 23.√74 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.7 (d) 8.6
  24. 24.√65 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.1 (d) 8.0
  25. 25.Best estimate of 1798 ÷ 68? (a) 2600 (b) 260 (c) 26
  26. 26.Best estimate of 2132 ÷ 27? (a) 7100 (b) 71 (c) 710
  27. 27.Best estimate of 365 ÷ 24? (a) 18 (b) 180 (c) 1800
  28. 28.Best estimate of 2442 ÷ 52? (a) 490 (b) 49 (c) 4900
  29. 29.√46 to 1 decimal place? (a) 6.8 (b) 6.5 (c) 6.7 (d) 6.6
  30. 30.√80 to 1 decimal place? (a) 9.1 (b) 8.9 (c) 9.0 (d) 8.8
  31. 31.√27 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.4 (d) 5.5
  32. 32.Best estimate of 2181 ÷ 86? (a) 24 (b) 2400 (c) 240
  33. 33.√55 to 1 decimal place? (a) 7.4 (b) 7.2 (c) 7.1 (d) 7.3
  34. 34.Best estimate of 3306 ÷ 39? (a) 83 (b) 830 (c) 8300
  35. 35.√56 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.5 (d) 7.8
  36. 36.Best estimate of 4339 ÷ 68? (a) 6200 (b) 62 (c) 620
  37. 37.Best estimate of 1052 ÷ 33? (a) 3500 (b) 350 (c) 35
  38. 38.Best estimate of 922 ÷ 22? (a) 460 (b) 46 (c) 4600
  39. 39.√76 to 1 decimal place? (a) 8.9 (b) 8.7 (c) 8.6 (d) 8.8
  40. 40.Best estimate of 4904 ÷ 62? (a) 8200 (b) 820 (c) 82

Answer key

  1. 41
  2. 26
  3. 44
  4. 64
  5. 7.9
  6. 7.8
  7. 56
  8. 5.3
  9. 7.6
  10. 9.9
  11. 9.8
  12. 8.7
  13. 13
  14. 51
  15. 5.7
  16. 20
  17. 4.6
  18. 72
  19. 28
  20. 5.8
  21. 9.7
  22. 14
  23. 8.6
  24. 8.1
  25. 26
  26. 71
  27. 18
  28. 49
  29. 6.8
  30. 8.9
  31. 5.2
  32. 24
  33. 7.4
  34. 83
  35. 7.5
  36. 62
  37. 35
  38. 46
  39. 8.7
  40. 82

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