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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 478 · 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 1062 ÷ 41? (a) 2700 (b) 27 (c) 270
  2. 2.Best estimate of 771 ÷ 49? (a) 1500 (b) 150 (c) 15
  3. 3.√72 to 1 decimal place? (a) 8.3 (b) 8.5 (c) 8.4 (d) 8.2
  4. 4.√26 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.1 (d) 5.4
  5. 5.Best estimate of 4624 ÷ 56? (a) 7700 (b) 770 (c) 77
  6. 6.Best estimate of 1449 ÷ 21? (a) 720 (b) 7200 (c) 72
  7. 7.Best estimate of 4480 ÷ 77? (a) 56 (b) 560 (c) 5600
  8. 8.Best estimate of 6743 ÷ 74? (a) 9600 (b) 960 (c) 96
  9. 9.√50 to 1 decimal place? (a) 7.3 (b) 7.1 (c) 7.2 (d) 7.0
  10. 10.Best estimate of 1147 ÷ 52? (a) 23 (b) 2300 (c) 230
  11. 11.Best estimate of 2633 ÷ 59? (a) 44 (b) 440 (c) 4400
  12. 12.√89 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.3 (d) 9.4
  13. 13.Best estimate of 4274 ÷ 79? (a) 53 (b) 530 (c) 5300
  14. 14.Best estimate of 6194 ÷ 81? (a) 770 (b) 7700 (c) 77
  15. 15.Best estimate of 2409 ÷ 56? (a) 4000 (b) 40 (c) 400
  16. 16.√34 to 1 decimal place? (a) 5.9 (b) 5.7 (c) 5.8 (d) 6.0
  17. 17.√77 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.6 (d) 8.9
  18. 18.√69 to 1 decimal place? (a) 8.3 (b) 8.5 (c) 8.4 (d) 8.6
  19. 19.√63 to 1 decimal place? (a) 7.7 (b) 7.9 (c) 7.8 (d) 7.6
  20. 20.Best estimate of 6320 ÷ 84? (a) 79 (b) 7900 (c) 790
  21. 21.Best estimate of 4648 ÷ 86? (a) 520 (b) 52 (c) 5200
  22. 22.Best estimate of 2887 ÷ 53? (a) 58 (b) 580 (c) 5800
  23. 23.√83 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.0 (d) 9.1
  24. 24.Best estimate of 2104 ÷ 32? (a) 700 (b) 7000 (c) 70
  25. 25.Best estimate of 1996 ÷ 21? (a) 1000 (b) 100 (c) 10000
  26. 26.Best estimate of 5116 ÷ 89? (a) 5700 (b) 570 (c) 57
  27. 27.√98 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 9.7 (d) 9.6
  28. 28.Best estimate of 4406 ÷ 49? (a) 880 (b) 88 (c) 8800
  29. 29.√96 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 10.0 (d) 10.1
  30. 30.√27 to 1 decimal place? (a) 5.2 (b) 5.4 (c) 5.3 (d) 5.5
  31. 31.Best estimate of 269 ÷ 21? (a) 1300 (b) 13 (c) 130
  32. 32.√92 to 1 decimal place? (a) 9.8 (b) 9.6 (c) 9.9 (d) 9.7
  33. 33.Best estimate of 913 ÷ 51? (a) 180 (b) 18 (c) 1800
  34. 34.√38 to 1 decimal place? (a) 6.2 (b) 6.1 (c) 6.3 (d) 6.0
  35. 35.√51 to 1 decimal place? (a) 7.1 (b) 7.0 (c) 7.2 (d) 7.3
  36. 36.√75 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.9 (d) 9.0
  37. 37.Best estimate of 2360 ÷ 78? (a) 300 (b) 3000 (c) 30
  38. 38.√43 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 6.7 (d) 6.6
  39. 39.√94 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.8 (d) 9.5
  40. 40.Best estimate of 1864 ÷ 54? (a) 370 (b) 3700 (c) 37

Answer key

  1. 27
  2. 15
  3. 8.5
  4. 5.1
  5. 77
  6. 72
  7. 56
  8. 96
  9. 7.1
  10. 23
  11. 44
  12. 9.4
  13. 53
  14. 77
  15. 40
  16. 5.8
  17. 8.8
  18. 8.3
  19. 7.9
  20. 79
  21. 52
  22. 58
  23. 9.1
  24. 70
  25. 100
  26. 57
  27. 9.9
  28. 88
  29. 9.8
  30. 5.2
  31. 13
  32. 9.6
  33. 18
  34. 6.2
  35. 7.1
  36. 8.7
  37. 30
  38. 6.6
  39. 9.7
  40. 37

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