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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 134 · 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.√46 to 1 decimal place? (a) 6.6 (b) 6.8 (c) 6.7 (d) 6.5
  2. 2.√83 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 9.1 (d) 9.2
  3. 3.Best estimate of 6141 ÷ 76? (a) 770 (b) 7700 (c) 77
  4. 4.√37 to 1 decimal place? (a) 6.2 (b) 6.0 (c) 6.3 (d) 6.1
  5. 5.Best estimate of 4487 ÷ 62? (a) 7500 (b) 750 (c) 75
  6. 6.√44 to 1 decimal place? (a) 6.6 (b) 6.3 (c) 6.4 (d) 6.5
  7. 7.Best estimate of 1456 ÷ 33? (a) 490 (b) 4900 (c) 49
  8. 8.Best estimate of 1670 ÷ 51? (a) 33 (b) 3300 (c) 330
  9. 9.√98 to 1 decimal place? (a) 10.2 (b) 10.1 (c) 9.9 (d) 10.0
  10. 10.Best estimate of 1025 ÷ 66? (a) 1500 (b) 150 (c) 15
  11. 11.√52 to 1 decimal place? (a) 7.1 (b) 7.0 (c) 7.3 (d) 7.2
  12. 12.Best estimate of 1419 ÷ 28? (a) 47 (b) 4700 (c) 470
  13. 13.Best estimate of 5596 ÷ 62? (a) 930 (b) 93 (c) 9300
  14. 14.Best estimate of 5013 ÷ 53? (a) 1000 (b) 100 (c) 10000
  15. 15.Best estimate of 625 ÷ 32? (a) 2100 (b) 210 (c) 21
  16. 16.Best estimate of 3462 ÷ 82? (a) 4300 (b) 43 (c) 430
  17. 17.√69 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 8.4 (d) 8.3
  18. 18.Best estimate of 4410 ÷ 56? (a) 74 (b) 7400 (c) 740
  19. 19.Best estimate of 933 ÷ 36? (a) 230 (b) 2300 (c) 23
  20. 20.√40 to 1 decimal place? (a) 6.0 (b) 6.1 (c) 6.3 (d) 6.2
  21. 21.Best estimate of 1268 ÷ 48? (a) 2500 (b) 25 (c) 250
  22. 22.Best estimate of 3489 ÷ 86? (a) 3900 (b) 39 (c) 390
  23. 23.√55 to 1 decimal place? (a) 7.3 (b) 7.4 (c) 7.5 (d) 7.2
  24. 24.Best estimate of 3781 ÷ 86? (a) 4200 (b) 420 (c) 42
  25. 25.√75 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.9 (d) 8.6
  26. 26.√26 to 1 decimal place? (a) 5.1 (b) 5.2 (c) 5.3 (d) 5.0
  27. 27.Best estimate of 4465 ÷ 78? (a) 5600 (b) 560 (c) 56
  28. 28.Best estimate of 606 ÷ 28? (a) 200 (b) 20 (c) 2000
  29. 29.√71 to 1 decimal place? (a) 8.5 (b) 8.4 (c) 8.3 (d) 8.2
  30. 30.Best estimate of 2156 ÷ 69? (a) 3100 (b) 310 (c) 31
  31. 31.√28 to 1 decimal place? (a) 5.4 (b) 5.6 (c) 5.5 (d) 5.3
  32. 32.Best estimate of 2282 ÷ 26? (a) 76 (b) 760 (c) 7600
  33. 33.Best estimate of 4697 ÷ 66? (a) 670 (b) 6700 (c) 67
  34. 34.Best estimate of 4791 ÷ 89? (a) 53 (b) 5300 (c) 530
  35. 35.Best estimate of 2813 ÷ 59? (a) 47 (b) 470 (c) 4700
  36. 36.Best estimate of 3982 ÷ 71? (a) 57 (b) 5700 (c) 570
  37. 37.Best estimate of 6587 ÷ 83? (a) 820 (b) 8200 (c) 82
  38. 38.√70 to 1 decimal place? (a) 8.5 (b) 8.2 (c) 8.4 (d) 8.3
  39. 39.Best estimate of 1495 ÷ 44? (a) 3700 (b) 370 (c) 37
  40. 40.√72 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.4 (d) 8.5

Answer key

  1. 6.8
  2. 9.1
  3. 77
  4. 6.1
  5. 75
  6. 6.6
  7. 49
  8. 33
  9. 9.9
  10. 15
  11. 7.2
  12. 47
  13. 93
  14. 100
  15. 21
  16. 43
  17. 8.3
  18. 74
  19. 23
  20. 6.3
  21. 25
  22. 39
  23. 7.4
  24. 42
  25. 8.7
  26. 5.1
  27. 56
  28. 20
  29. 8.4
  30. 31
  31. 5.3
  32. 76
  33. 67
  34. 53
  35. 47
  36. 57
  37. 82
  38. 8.4
  39. 37
  40. 8.5

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