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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 156 · 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.√90 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.4 (d) 9.5
  2. 2.Best estimate of 6554 ÷ 77? (a) 8200 (b) 820 (c) 82
  3. 3.Best estimate of 1039 ÷ 53? (a) 2100 (b) 21 (c) 210
  4. 4.Best estimate of 6167 ÷ 83? (a) 7700 (b) 770 (c) 77
  5. 5.Best estimate of 5397 ÷ 74? (a) 770 (b) 7700 (c) 77
  6. 6.Best estimate of 4051 ÷ 72? (a) 58 (b) 5800 (c) 580
  7. 7.√88 to 1 decimal place? (a) 9.6 (b) 9.4 (c) 9.3 (d) 9.5
  8. 8.Best estimate of 3211 ÷ 71? (a) 46 (b) 460 (c) 4600
  9. 9.Best estimate of 637 ÷ 31? (a) 210 (b) 21 (c) 2100
  10. 10.Best estimate of 1652 ÷ 72? (a) 240 (b) 2400 (c) 24
  11. 11.Best estimate of 3322 ÷ 76? (a) 42 (b) 4200 (c) 420
  12. 12.Best estimate of 2179 ÷ 41? (a) 54 (b) 540 (c) 5400
  13. 13.Best estimate of 6205 ÷ 84? (a) 7800 (b) 78 (c) 780
  14. 14.Best estimate of 5244 ÷ 59? (a) 87 (b) 8700 (c) 870
  15. 15.Best estimate of 3457 ÷ 81? (a) 43 (b) 430 (c) 4300
  16. 16.Best estimate of 4602 ÷ 51? (a) 92 (b) 9200 (c) 920
  17. 17.√26 to 1 decimal place? (a) 5.2 (b) 5.4 (c) 5.3 (d) 5.1
  18. 18.√96 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 9.7 (d) 9.6
  19. 19.√98 to 1 decimal place? (a) 10.1 (b) 10.0 (c) 9.8 (d) 9.9
  20. 20.√53 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.1 (d) 7.0
  21. 21.Best estimate of 2432 ÷ 36? (a) 610 (b) 6100 (c) 61
  22. 22.Best estimate of 671 ÷ 21? (a) 3400 (b) 340 (c) 34
  23. 23.√42 to 1 decimal place? (a) 6.5 (b) 6.8 (c) 6.6 (d) 6.7
  24. 24.Best estimate of 1188 ÷ 43? (a) 3000 (b) 30 (c) 300
  25. 25.Best estimate of 2324 ÷ 26? (a) 7700 (b) 77 (c) 770
  26. 26.√86 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.3 (d) 9.5
  27. 27.Best estimate of 1726 ÷ 22? (a) 8600 (b) 86 (c) 860
  28. 28.Best estimate of 2080 ÷ 72? (a) 30 (b) 3000 (c) 300
  29. 29.Best estimate of 4478 ÷ 56? (a) 750 (b) 7500 (c) 75
  30. 30.√58 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.8 (d) 7.7
  31. 31.Best estimate of 1303 ÷ 74? (a) 1900 (b) 19 (c) 190
  32. 32.Best estimate of 4594 ÷ 57? (a) 7700 (b) 770 (c) 77
  33. 33.√34 to 1 decimal place? (a) 6.0 (b) 5.8 (c) 5.7 (d) 5.9
  34. 34.Best estimate of 3778 ÷ 52? (a) 7600 (b) 760 (c) 76
  35. 35.√38 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.4 (d) 6.1
  36. 36.Best estimate of 2620 ÷ 82? (a) 330 (b) 3300 (c) 33
  37. 37.Best estimate of 3432 ÷ 49? (a) 690 (b) 6900 (c) 69
  38. 38.√79 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 9.1 (d) 9.2
  39. 39.Best estimate of 1772 ÷ 28? (a) 59 (b) 590 (c) 5900
  40. 40.Best estimate of 1225 ÷ 47? (a) 25 (b) 250 (c) 2500

Answer key

  1. 9.5
  2. 82
  3. 21
  4. 77
  5. 77
  6. 58
  7. 9.4
  8. 46
  9. 21
  10. 24
  11. 42
  12. 54
  13. 78
  14. 87
  15. 43
  16. 92
  17. 5.1
  18. 9.8
  19. 9.9
  20. 7.3
  21. 61
  22. 34
  23. 6.5
  24. 30
  25. 77
  26. 9.3
  27. 86
  28. 30
  29. 75
  30. 7.6
  31. 19
  32. 77
  33. 5.8
  34. 76
  35. 6.2
  36. 33
  37. 69
  38. 8.9
  39. 59
  40. 25

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