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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 755 · 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 3843 ÷ 58? (a) 6400 (b) 64 (c) 640
  2. 2.Best estimate of 1238 ÷ 28? (a) 41 (b) 410 (c) 4100
  3. 3.√32 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.7 (d) 5.4
  4. 4.Best estimate of 851 ÷ 23? (a) 430 (b) 4300 (c) 43
  5. 5.Best estimate of 907 ÷ 23? (a) 45 (b) 4500 (c) 450
  6. 6.Best estimate of 5003 ÷ 71? (a) 710 (b) 7100 (c) 71
  7. 7.Best estimate of 3041 ÷ 64? (a) 51 (b) 5100 (c) 510
  8. 8.√92 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.9 (d) 9.6
  9. 9.√74 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.6 (d) 8.9
  10. 10.√88 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.5 (d) 9.2
  11. 11.Best estimate of 4362 ÷ 64? (a) 730 (b) 7300 (c) 73
  12. 12.Best estimate of 4385 ÷ 62? (a) 730 (b) 73 (c) 7300
  13. 13.√58 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.7 (d) 7.6
  14. 14.Best estimate of 1611 ÷ 66? (a) 23 (b) 2300 (c) 230
  15. 15.√82 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 8.9 (d) 9.0
  16. 16.Best estimate of 708 ÷ 44? (a) 18 (b) 1800 (c) 180
  17. 17.Best estimate of 2724 ÷ 62? (a) 4500 (b) 450 (c) 45
  18. 18.Best estimate of 5227 ÷ 56? (a) 8700 (b) 870 (c) 87
  19. 19.√31 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.9 (d) 5.8
  20. 20.Best estimate of 2015 ÷ 36? (a) 500 (b) 50 (c) 5000
  21. 21.√78 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 8.9 (d) 9.1
  22. 22.√47 to 1 decimal place? (a) 7.0 (b) 7.1 (c) 6.9 (d) 7.2
  23. 23.√52 to 1 decimal place? (a) 7.1 (b) 7.4 (c) 7.2 (d) 7.3
  24. 24.√51 to 1 decimal place? (a) 7.3 (b) 7.1 (c) 7.2 (d) 7.0
  25. 25.√89 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.4 (d) 9.7
  26. 26.√61 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 7.8 (d) 7.7
  27. 27.√28 to 1 decimal place? (a) 5.4 (b) 5.6 (c) 5.3 (d) 5.5
  28. 28.Best estimate of 383 ÷ 23? (a) 1900 (b) 19 (c) 190
  29. 29.Best estimate of 4783 ÷ 87? (a) 5300 (b) 530 (c) 53
  30. 30.Best estimate of 1229 ÷ 42? (a) 3100 (b) 31 (c) 310
  31. 31.Best estimate of 3076 ÷ 46? (a) 6200 (b) 620 (c) 62
  32. 32.Best estimate of 3932 ÷ 89? (a) 4400 (b) 44 (c) 440
  33. 33.Best estimate of 2219 ÷ 26? (a) 7400 (b) 74 (c) 740
  34. 34.√42 to 1 decimal place? (a) 6.5 (b) 6.3 (c) 6.4 (d) 6.2
  35. 35.Best estimate of 5277 ÷ 57? (a) 880 (b) 8800 (c) 88
  36. 36.Best estimate of 3839 ÷ 42? (a) 9600 (b) 960 (c) 96
  37. 37.Best estimate of 567 ÷ 42? (a) 140 (b) 14 (c) 1400
  38. 38.Best estimate of 4616 ÷ 82? (a) 58 (b) 5800 (c) 580
  39. 39.Best estimate of 2546 ÷ 49? (a) 51 (b) 510 (c) 5100
  40. 40.√96 to 1 decimal place? (a) 10.1 (b) 9.9 (c) 10.0 (d) 9.8

Answer key

  1. 64
  2. 41
  3. 5.7
  4. 43
  5. 45
  6. 71
  7. 51
  8. 9.6
  9. 8.6
  10. 9.4
  11. 73
  12. 73
  13. 7.6
  14. 23
  15. 9.1
  16. 18
  17. 45
  18. 87
  19. 5.6
  20. 50
  21. 8.8
  22. 6.9
  23. 7.2
  24. 7.1
  25. 9.4
  26. 7.8
  27. 5.3
  28. 19
  29. 53
  30. 31
  31. 62
  32. 44
  33. 74
  34. 6.5
  35. 88
  36. 96
  37. 14
  38. 58
  39. 51
  40. 9.8

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