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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 190 · 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.√94 to 1 decimal place? (a) 9.9 (b) 9.7 (c) 9.6 (d) 9.8
  2. 2.√53 to 1 decimal place? (a) 7.5 (b) 7.2 (c) 7.3 (d) 7.4
  3. 3.√98 to 1 decimal place? (a) 9.8 (b) 10.0 (c) 9.9 (d) 9.7
  4. 4.√35 to 1 decimal place? (a) 5.9 (b) 6.1 (c) 6.0 (d) 5.8
  5. 5.Best estimate of 4952 ÷ 54? (a) 990 (b) 9900 (c) 99
  6. 6.√61 to 1 decimal place? (a) 8.0 (b) 7.7 (c) 7.9 (d) 7.8
  7. 7.Best estimate of 815 ÷ 33? (a) 270 (b) 27 (c) 2700
  8. 8.√27 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 5.2 (d) 5.1
  9. 9.Best estimate of 3640 ÷ 84? (a) 460 (b) 46 (c) 4600
  10. 10.Best estimate of 1950 ÷ 29? (a) 6500 (b) 65 (c) 650
  11. 11.Best estimate of 4511 ÷ 76? (a) 56 (b) 560 (c) 5600
  12. 12.Best estimate of 1543 ÷ 24? (a) 7700 (b) 770 (c) 77
  13. 13.Best estimate of 1331 ÷ 34? (a) 4400 (b) 440 (c) 44
  14. 14.√44 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.4 (d) 6.5
  15. 15.Best estimate of 2419 ÷ 77? (a) 300 (b) 3000 (c) 30
  16. 16.√51 to 1 decimal place? (a) 6.9 (b) 7.2 (c) 7.1 (d) 7.0
  17. 17.Best estimate of 635 ÷ 32? (a) 21 (b) 210 (c) 2100
  18. 18.√50 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.3 (d) 7.4
  19. 19.√96 to 1 decimal place? (a) 9.9 (b) 9.7 (c) 10.0 (d) 9.8
  20. 20.Best estimate of 5452 ÷ 77? (a) 680 (b) 68 (c) 6800
  21. 21.Best estimate of 1414 ÷ 56? (a) 24 (b) 240 (c) 2400
  22. 22.√22 to 1 decimal place? (a) 4.7 (b) 4.4 (c) 4.6 (d) 4.5
  23. 23.Best estimate of 1578 ÷ 42? (a) 3900 (b) 390 (c) 39
  24. 24.Best estimate of 483 ÷ 37? (a) 12 (b) 1200 (c) 120
  25. 25.Best estimate of 1827 ÷ 34? (a) 6100 (b) 610 (c) 61
  26. 26.√67 to 1 decimal place? (a) 8.4 (b) 8.2 (c) 8.3 (d) 8.1
  27. 27.Best estimate of 3172 ÷ 48? (a) 630 (b) 63 (c) 6300
  28. 28.√63 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 7.8 (d) 8.1
  29. 29.√56 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.7 (d) 7.8
  30. 30.Best estimate of 2204 ÷ 86? (a) 2400 (b) 240 (c) 24
  31. 31.Best estimate of 694 ÷ 21? (a) 350 (b) 3500 (c) 35
  32. 32.Best estimate of 1630 ÷ 21? (a) 820 (b) 8200 (c) 82
  33. 33.√28 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.4 (d) 5.3
  34. 34.Best estimate of 2910 ÷ 49? (a) 5800 (b) 58 (c) 580
  35. 35.Best estimate of 879 ÷ 66? (a) 13 (b) 1300 (c) 130
  36. 36.Best estimate of 3063 ÷ 51? (a) 6100 (b) 61 (c) 610
  37. 37.√37 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 6.1 (d) 5.8
  38. 38.√83 to 1 decimal place? (a) 9.2 (b) 8.9 (c) 9.1 (d) 9.0
  39. 39.√86 to 1 decimal place? (a) 9.3 (b) 9.5 (c) 9.4 (d) 9.2
  40. 40.Best estimate of 5381 ÷ 58? (a) 900 (b) 9000 (c) 90

Answer key

  1. 9.7
  2. 7.3
  3. 9.9
  4. 5.9
  5. 99
  6. 7.8
  7. 27
  8. 5.2
  9. 46
  10. 65
  11. 56
  12. 77
  13. 44
  14. 6.6
  15. 30
  16. 7.1
  17. 21
  18. 7.1
  19. 9.8
  20. 68
  21. 24
  22. 4.7
  23. 39
  24. 12
  25. 61
  26. 8.2
  27. 63
  28. 7.9
  29. 7.5
  30. 24
  31. 35
  32. 82
  33. 5.3
  34. 58
  35. 13
  36. 61
  37. 6.1
  38. 9.1
  39. 9.3
  40. 90

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