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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 388 · 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 1439 ÷ 51? (a) 2900 (b) 29 (c) 290
  2. 2.√90 to 1 decimal place? (a) 9.7 (b) 9.5 (c) 9.4 (d) 9.6
  3. 3.Best estimate of 2700 ÷ 69? (a) 390 (b) 39 (c) 3900
  4. 4.Best estimate of 1694 ÷ 33? (a) 56 (b) 560 (c) 5600
  5. 5.√26 to 1 decimal place? (a) 5.1 (b) 5.0 (c) 5.2 (d) 4.9
  6. 6.Best estimate of 3843 ÷ 53? (a) 77 (b) 770 (c) 7700
  7. 7.Best estimate of 2606 ÷ 84? (a) 3300 (b) 330 (c) 33
  8. 8.√77 to 1 decimal place? (a) 8.6 (b) 8.8 (c) 8.7 (d) 8.9
  9. 9.Best estimate of 1841 ÷ 42? (a) 46 (b) 4600 (c) 460
  10. 10.√75 to 1 decimal place? (a) 8.7 (b) 9.0 (c) 8.8 (d) 8.9
  11. 11.√59 to 1 decimal place? (a) 7.9 (b) 7.7 (c) 7.8 (d) 7.6
  12. 12.Best estimate of 1913 ÷ 36? (a) 4800 (b) 48 (c) 480
  13. 13.Best estimate of 2657 ÷ 47? (a) 53 (b) 5300 (c) 530
  14. 14.Best estimate of 707 ÷ 26? (a) 2400 (b) 24 (c) 240
  15. 15.√71 to 1 decimal place? (a) 8.5 (b) 8.4 (c) 8.6 (d) 8.3
  16. 16.√88 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.4 (d) 9.6
  17. 17.Best estimate of 4699 ÷ 84? (a) 59 (b) 5900 (c) 590
  18. 18.Best estimate of 1795 ÷ 24? (a) 900 (b) 90 (c) 9000
  19. 19.Best estimate of 3081 ÷ 33? (a) 103 (b) 10300 (c) 1030
  20. 20.Best estimate of 635 ÷ 32? (a) 210 (b) 2100 (c) 21
  21. 21.Best estimate of 3097 ÷ 53? (a) 620 (b) 6200 (c) 62
  22. 22.Best estimate of 2574 ÷ 27? (a) 86 (b) 8600 (c) 860
  23. 23.Best estimate of 3785 ÷ 76? (a) 47 (b) 470 (c) 4700
  24. 24.Best estimate of 2296 ÷ 29? (a) 77 (b) 7700 (c) 770
  25. 25.Best estimate of 1560 ÷ 73? (a) 2200 (b) 220 (c) 22
  26. 26.√21 to 1 decimal place? (a) 4.6 (b) 4.9 (c) 4.7 (d) 4.8
  27. 27.Best estimate of 3287 ÷ 44? (a) 8200 (b) 82 (c) 820
  28. 28.Best estimate of 6087 ÷ 82? (a) 7600 (b) 76 (c) 760
  29. 29.Best estimate of 965 ÷ 36? (a) 240 (b) 2400 (c) 24
  30. 30.Best estimate of 4441 ÷ 66? (a) 6300 (b) 630 (c) 63
  31. 31.Best estimate of 859 ÷ 67? (a) 12 (b) 120 (c) 1200
  32. 32.Best estimate of 4045 ÷ 53? (a) 8100 (b) 810 (c) 81
  33. 33.√37 to 1 decimal place? (a) 6.2 (b) 6.1 (c) 6.3 (d) 6.0
  34. 34.√82 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.0 (d) 9.3
  35. 35.√78 to 1 decimal place? (a) 9.0 (b) 8.8 (c) 8.7 (d) 8.9
  36. 36.Best estimate of 6140 ÷ 74? (a) 880 (b) 88 (c) 8800
  37. 37.Best estimate of 3921 ÷ 42? (a) 9800 (b) 98 (c) 980
  38. 38.Best estimate of 536 ÷ 27? (a) 18 (b) 1800 (c) 180
  39. 39.Best estimate of 717 ÷ 24? (a) 3600 (b) 36 (c) 360
  40. 40.√22 to 1 decimal place? (a) 5.0 (b) 4.7 (c) 4.8 (d) 4.9

Answer key

  1. 29
  2. 9.5
  3. 39
  4. 56
  5. 5.1
  6. 77
  7. 33
  8. 8.8
  9. 46
  10. 8.7
  11. 7.7
  12. 48
  13. 53
  14. 24
  15. 8.4
  16. 9.4
  17. 59
  18. 90
  19. 103
  20. 21
  21. 62
  22. 86
  23. 47
  24. 77
  25. 22
  26. 4.6
  27. 82
  28. 76
  29. 24
  30. 63
  31. 12
  32. 81
  33. 6.1
  34. 9.1
  35. 8.8
  36. 88
  37. 98
  38. 18
  39. 36
  40. 4.7

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