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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 24 · 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.√82 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.4 (d) 9.1
  2. 2.Best estimate of 1639 ÷ 24? (a) 8200 (b) 82 (c) 820
  3. 3.√35 to 1 decimal place? (a) 5.9 (b) 6.1 (c) 5.8 (d) 6.0
  4. 4.√23 to 1 decimal place? (a) 4.6 (b) 4.8 (c) 4.5 (d) 4.7
  5. 5.Best estimate of 499 ÷ 22? (a) 250 (b) 2500 (c) 25
  6. 6.Best estimate of 3068 ÷ 67? (a) 4400 (b) 440 (c) 44
  7. 7.Best estimate of 2683 ÷ 39? (a) 670 (b) 67 (c) 6700
  8. 8.√40 to 1 decimal place? (a) 6.4 (b) 6.2 (c) 6.3 (d) 6.5
  9. 9.Best estimate of 3552 ÷ 63? (a) 590 (b) 5900 (c) 59
  10. 10.Best estimate of 892 ÷ 46? (a) 1800 (b) 18 (c) 180
  11. 11.Best estimate of 3948 ÷ 72? (a) 560 (b) 5600 (c) 56
  12. 12.Best estimate of 709 ÷ 22? (a) 35 (b) 350 (c) 3500
  13. 13.√75 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 9.0 (d) 8.9
  14. 14.√31 to 1 decimal place? (a) 5.8 (b) 5.7 (c) 5.5 (d) 5.6
  15. 15.Best estimate of 674 ÷ 27? (a) 220 (b) 2200 (c) 22
  16. 16.Best estimate of 4773 ÷ 62? (a) 800 (b) 8000 (c) 80
  17. 17.√41 to 1 decimal place? (a) 6.5 (b) 6.4 (c) 6.6 (d) 6.3
  18. 18.Best estimate of 1699 ÷ 42? (a) 42 (b) 420 (c) 4200
  19. 19.Best estimate of 2799 ÷ 82? (a) 3500 (b) 350 (c) 35
  20. 20.Best estimate of 5042 ÷ 56? (a) 840 (b) 8400 (c) 84
  21. 21.√42 to 1 decimal place? (a) 6.8 (b) 6.6 (c) 6.7 (d) 6.5
  22. 22.Best estimate of 2442 ÷ 68? (a) 350 (b) 35 (c) 3500
  23. 23.√24 to 1 decimal place? (a) 5.2 (b) 5.0 (c) 5.1 (d) 4.9
  24. 24.√58 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 7.7 (d) 7.6
  25. 25.√55 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.3 (d) 7.4
  26. 26.Best estimate of 4058 ÷ 71? (a) 580 (b) 5800 (c) 58
  27. 27.Best estimate of 3227 ÷ 62? (a) 54 (b) 540 (c) 5400
  28. 28.Best estimate of 5513 ÷ 62? (a) 920 (b) 9200 (c) 92
  29. 29.√29 to 1 decimal place? (a) 5.5 (b) 5.2 (c) 5.4 (d) 5.3
  30. 30.Best estimate of 905 ÷ 22? (a) 45 (b) 4500 (c) 450
  31. 31.Best estimate of 4381 ÷ 46? (a) 88 (b) 8800 (c) 880
  32. 32.Best estimate of 960 ÷ 36? (a) 2400 (b) 240 (c) 24
  33. 33.√21 to 1 decimal place? (a) 4.9 (b) 4.7 (c) 4.8 (d) 4.6
  34. 34.Best estimate of 3979 ÷ 72? (a) 5700 (b) 57 (c) 570
  35. 35.Best estimate of 2032 ÷ 73? (a) 29 (b) 2900 (c) 290
  36. 36.√92 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.6 (d) 9.5
  37. 37.Best estimate of 1752 ÷ 43? (a) 440 (b) 44 (c) 4400
  38. 38.Best estimate of 3341 ÷ 81? (a) 4200 (b) 42 (c) 420
  39. 39.√47 to 1 decimal place? (a) 7.1 (b) 6.9 (c) 7.0 (d) 6.8
  40. 40.√34 to 1 decimal place? (a) 5.6 (b) 5.8 (c) 5.9 (d) 5.7

Answer key

  1. 9.1
  2. 82
  3. 5.9
  4. 4.8
  5. 25
  6. 44
  7. 67
  8. 6.3
  9. 59
  10. 18
  11. 56
  12. 35
  13. 8.7
  14. 5.6
  15. 22
  16. 80
  17. 6.4
  18. 42
  19. 35
  20. 84
  21. 6.5
  22. 35
  23. 4.9
  24. 7.6
  25. 7.4
  26. 58
  27. 54
  28. 92
  29. 5.4
  30. 45
  31. 88
  32. 24
  33. 4.6
  34. 57
  35. 29
  36. 9.6
  37. 44
  38. 42
  39. 6.9
  40. 5.8

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