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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 578 · 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 2920 ÷ 51? (a) 580 (b) 58 (c) 5800
  2. 2.√77 to 1 decimal place? (a) 9.1 (b) 8.9 (c) 8.8 (d) 9.0
  3. 3.Best estimate of 1444 ÷ 21? (a) 720 (b) 72 (c) 7200
  4. 4.Best estimate of 3179 ÷ 49? (a) 640 (b) 6400 (c) 64
  5. 5.√41 to 1 decimal place? (a) 6.5 (b) 6.4 (c) 6.6 (d) 6.7
  6. 6.√42 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 6.6 (d) 6.5
  7. 7.Best estimate of 5501 ÷ 74? (a) 7900 (b) 79 (c) 790
  8. 8.Best estimate of 2696 ÷ 34? (a) 90 (b) 900 (c) 9000
  9. 9.√50 to 1 decimal place? (a) 6.9 (b) 7.1 (c) 7.0 (d) 6.8
  10. 10.√62 to 1 decimal place? (a) 8.1 (b) 7.9 (c) 7.8 (d) 8.0
  11. 11.√26 to 1 decimal place? (a) 5.1 (b) 5.2 (c) 4.9 (d) 5.0
  12. 12.Best estimate of 817 ÷ 21? (a) 41 (b) 4100 (c) 410
  13. 13.√32 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.8 (d) 5.9
  14. 14.Best estimate of 2765 ÷ 62? (a) 460 (b) 46 (c) 4600
  15. 15.Best estimate of 1023 ÷ 21? (a) 51 (b) 5100 (c) 510
  16. 16.Best estimate of 826 ÷ 49? (a) 170 (b) 1700 (c) 17
  17. 17.Best estimate of 2468 ÷ 29? (a) 820 (b) 8200 (c) 82
  18. 18.√37 to 1 decimal place? (a) 6.3 (b) 6.0 (c) 6.2 (d) 6.1
  19. 19.√46 to 1 decimal place? (a) 7.0 (b) 6.9 (c) 6.7 (d) 6.8
  20. 20.√63 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.1 (d) 7.8
  21. 21.√87 to 1 decimal place? (a) 9.3 (b) 9.1 (c) 9.2 (d) 9.0
  22. 22.Best estimate of 1803 ÷ 46? (a) 36 (b) 3600 (c) 360
  23. 23.Best estimate of 3748 ÷ 53? (a) 75 (b) 750 (c) 7500
  24. 24.√55 to 1 decimal place? (a) 7.2 (b) 7.4 (c) 7.3 (d) 7.5
  25. 25.Best estimate of 4683 ÷ 66? (a) 6700 (b) 670 (c) 67
  26. 26.Best estimate of 1842 ÷ 42? (a) 46 (b) 4600 (c) 460
  27. 27.Best estimate of 2128 ÷ 59? (a) 350 (b) 3500 (c) 35
  28. 28.Best estimate of 4930 ÷ 71? (a) 700 (b) 70 (c) 7000
  29. 29.Best estimate of 3602 ÷ 58? (a) 6000 (b) 60 (c) 600
  30. 30.√83 to 1 decimal place? (a) 9.1 (b) 8.9 (c) 9.0 (d) 9.2
  31. 31.Best estimate of 3352 ÷ 41? (a) 8400 (b) 840 (c) 84
  32. 32.√84 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.4 (d) 9.2
  33. 33.Best estimate of 1151 ÷ 38? (a) 29 (b) 290 (c) 2900
  34. 34.√35 to 1 decimal place? (a) 5.9 (b) 5.8 (c) 5.7 (d) 6.0
  35. 35.Best estimate of 2498 ÷ 64? (a) 42 (b) 4200 (c) 420
  36. 36.Best estimate of 3672 ÷ 52? (a) 7300 (b) 730 (c) 73
  37. 37.√82 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.0 (d) 9.3
  38. 38.Best estimate of 2275 ÷ 52? (a) 4600 (b) 46 (c) 460
  39. 39.√28 to 1 decimal place? (a) 5.3 (b) 5.1 (c) 5.0 (d) 5.2
  40. 40.Best estimate of 1087 ÷ 47? (a) 22 (b) 220 (c) 2200

Answer key

  1. 58
  2. 8.8
  3. 72
  4. 64
  5. 6.4
  6. 6.5
  7. 79
  8. 90
  9. 7.1
  10. 7.9
  11. 5.1
  12. 41
  13. 5.7
  14. 46
  15. 51
  16. 17
  17. 82
  18. 6.1
  19. 6.8
  20. 7.9
  21. 9.3
  22. 36
  23. 75
  24. 7.4
  25. 67
  26. 46
  27. 35
  28. 70
  29. 60
  30. 9.1
  31. 84
  32. 9.2
  33. 29
  34. 5.9
  35. 42
  36. 73
  37. 9.1
  38. 46
  39. 5.3
  40. 22

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