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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 376 · 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 935 ÷ 43? (a) 2300 (b) 23 (c) 230
  2. 2.√72 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.7 (d) 8.8
  3. 3.Best estimate of 5760 ÷ 66? (a) 8200 (b) 820 (c) 82
  4. 4.√62 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 7.9 (d) 7.8
  5. 5.√75 to 1 decimal place? (a) 8.7 (b) 8.4 (c) 8.5 (d) 8.6
  6. 6.Best estimate of 1827 ÷ 42? (a) 46 (b) 4600 (c) 460
  7. 7.Best estimate of 4225 ÷ 54? (a) 8500 (b) 850 (c) 85
  8. 8.√26 to 1 decimal place? (a) 5.2 (b) 5.4 (c) 5.3 (d) 5.1
  9. 9.√98 to 1 decimal place? (a) 10.1 (b) 10.0 (c) 10.2 (d) 9.9
  10. 10.√40 to 1 decimal place? (a) 6.1 (b) 6.4 (c) 6.3 (d) 6.2
  11. 11.√69 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.3 (d) 8.2
  12. 12.Best estimate of 1281 ÷ 47? (a) 2600 (b) 260 (c) 26
  13. 13.√61 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 7.9 (d) 7.8
  14. 14.Best estimate of 1069 ÷ 69? (a) 150 (b) 1500 (c) 15
  15. 15.Best estimate of 1235 ÷ 21? (a) 62 (b) 6200 (c) 620
  16. 16.Best estimate of 824 ÷ 66? (a) 120 (b) 12 (c) 1200
  17. 17.Best estimate of 6897 ÷ 77? (a) 860 (b) 86 (c) 8600
  18. 18.Best estimate of 1951 ÷ 59? (a) 3300 (b) 330 (c) 33
  19. 19.Best estimate of 638 ÷ 21? (a) 3200 (b) 320 (c) 32
  20. 20.Best estimate of 4673 ÷ 82? (a) 58 (b) 580 (c) 5800
  21. 21.Best estimate of 1266 ÷ 48? (a) 2500 (b) 25 (c) 250
  22. 22.√24 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.9 (d) 4.8
  23. 23.√23 to 1 decimal place? (a) 4.9 (b) 4.7 (c) 4.8 (d) 4.6
  24. 24.√48 to 1 decimal place? (a) 6.9 (b) 6.7 (c) 7.0 (d) 6.8
  25. 25.√58 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.8 (d) 7.5
  26. 26.√51 to 1 decimal place? (a) 7.1 (b) 6.9 (c) 7.2 (d) 7.0
  27. 27.√84 to 1 decimal place? (a) 9.2 (b) 9.0 (c) 9.1 (d) 9.3
  28. 28.Best estimate of 5202 ÷ 71? (a) 7400 (b) 740 (c) 74
  29. 29.Best estimate of 1157 ÷ 22? (a) 580 (b) 58 (c) 5800
  30. 30.√30 to 1 decimal place? (a) 5.4 (b) 5.5 (c) 5.7 (d) 5.6
  31. 31.√92 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 9.6 (d) 9.7
  32. 32.Best estimate of 1372 ÷ 22? (a) 6900 (b) 690 (c) 69
  33. 33.Best estimate of 3557 ÷ 79? (a) 4400 (b) 440 (c) 44
  34. 34.Best estimate of 3317 ÷ 43? (a) 830 (b) 83 (c) 8300
  35. 35.Best estimate of 3212 ÷ 82? (a) 4000 (b) 40 (c) 400
  36. 36.Best estimate of 3366 ÷ 46? (a) 670 (b) 6700 (c) 67
  37. 37.√21 to 1 decimal place? (a) 4.5 (b) 4.6 (c) 4.4 (d) 4.7
  38. 38.Best estimate of 3335 ÷ 82? (a) 420 (b) 42 (c) 4200
  39. 39.Best estimate of 1429 ÷ 22? (a) 710 (b) 7100 (c) 71
  40. 40.Best estimate of 4840 ÷ 56? (a) 81 (b) 810 (c) 8100

Answer key

  1. 23
  2. 8.5
  3. 82
  4. 7.9
  5. 8.7
  6. 46
  7. 85
  8. 5.1
  9. 9.9
  10. 6.3
  11. 8.3
  12. 26
  13. 7.8
  14. 15
  15. 62
  16. 12
  17. 86
  18. 33
  19. 32
  20. 58
  21. 25
  22. 4.9
  23. 4.8
  24. 6.9
  25. 7.6
  26. 7.1
  27. 9.2
  28. 74
  29. 58
  30. 5.5
  31. 9.6
  32. 69
  33. 44
  34. 83
  35. 40
  36. 67
  37. 4.6
  38. 42
  39. 71
  40. 81

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