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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 164 · 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 526 ÷ 42? (a) 1300 (b) 130 (c) 13
  2. 2.√82 to 1 decimal place? (a) 9.2 (b) 9.0 (c) 8.9 (d) 9.1
  3. 3.Best estimate of 964 ÷ 33? (a) 3200 (b) 32 (c) 320
  4. 4.Best estimate of 3850 ÷ 43? (a) 96 (b) 9600 (c) 960
  5. 5.Best estimate of 2680 ÷ 39? (a) 6700 (b) 67 (c) 670
  6. 6.Best estimate of 2538 ÷ 69? (a) 3600 (b) 36 (c) 360
  7. 7.√71 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.5 (d) 8.4
  8. 8.Best estimate of 2581 ÷ 36? (a) 6500 (b) 650 (c) 65
  9. 9.√94 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.4 (d) 9.6
  10. 10.Best estimate of 7272 ÷ 78? (a) 91 (b) 910 (c) 9100
  11. 11.Best estimate of 1734 ÷ 26? (a) 580 (b) 58 (c) 5800
  12. 12.√26 to 1 decimal place? (a) 5.2 (b) 5.1 (c) 5.3 (d) 5.0
  13. 13.√44 to 1 decimal place? (a) 6.4 (b) 6.6 (c) 6.7 (d) 6.5
  14. 14.Best estimate of 1923 ÷ 27? (a) 64 (b) 640 (c) 6400
  15. 15.√21 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 4.6 (d) 4.5
  16. 16.√50 to 1 decimal place? (a) 7.1 (b) 7.4 (c) 7.2 (d) 7.3
  17. 17.√35 to 1 decimal place? (a) 6.2 (b) 5.9 (c) 6.0 (d) 6.1
  18. 18.√83 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 8.9 (d) 9.2
  19. 19.Best estimate of 1414 ÷ 38? (a) 3500 (b) 35 (c) 350
  20. 20.Best estimate of 2247 ÷ 32? (a) 7500 (b) 75 (c) 750
  21. 21.√52 to 1 decimal place? (a) 7.2 (b) 7.4 (c) 7.3 (d) 7.5
  22. 22.Best estimate of 886 ÷ 34? (a) 3000 (b) 300 (c) 30
  23. 23.√53 to 1 decimal place? (a) 7.5 (b) 7.4 (c) 7.3 (d) 7.6
  24. 24.Best estimate of 1183 ÷ 67? (a) 1700 (b) 17 (c) 170
  25. 25.√65 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 8.3 (d) 8.0
  26. 26.√23 to 1 decimal place? (a) 4.5 (b) 4.6 (c) 4.7 (d) 4.8
  27. 27.Best estimate of 3092 ÷ 52? (a) 620 (b) 6200 (c) 62
  28. 28.Best estimate of 922 ÷ 36? (a) 23 (b) 230 (c) 2300
  29. 29.√40 to 1 decimal place? (a) 6.2 (b) 6.1 (c) 6.0 (d) 6.3
  30. 30.√55 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.3 (d) 7.5
  31. 31.Best estimate of 3592 ÷ 86? (a) 4000 (b) 40 (c) 400
  32. 32.√51 to 1 decimal place? (a) 7.3 (b) 7.0 (c) 7.1 (d) 7.2
  33. 33.Best estimate of 1491 ÷ 52? (a) 300 (b) 3000 (c) 30
  34. 34.Best estimate of 822 ÷ 26? (a) 27 (b) 270 (c) 2700
  35. 35.Best estimate of 1915 ÷ 47? (a) 3800 (b) 38 (c) 380
  36. 36.Best estimate of 6956 ÷ 78? (a) 8700 (b) 870 (c) 87
  37. 37.√30 to 1 decimal place? (a) 5.7 (b) 5.4 (c) 5.6 (d) 5.5
  38. 38.Best estimate of 432 ÷ 22? (a) 22 (b) 2200 (c) 220
  39. 39.Best estimate of 3807 ÷ 51? (a) 76 (b) 7600 (c) 760
  40. 40.Best estimate of 6448 ÷ 68? (a) 9200 (b) 92 (c) 920

Answer key

  1. 13
  2. 9.1
  3. 32
  4. 96
  5. 67
  6. 36
  7. 8.4
  8. 65
  9. 9.7
  10. 91
  11. 58
  12. 5.1
  13. 6.6
  14. 64
  15. 4.6
  16. 7.1
  17. 5.9
  18. 9.1
  19. 35
  20. 75
  21. 7.2
  22. 30
  23. 7.3
  24. 17
  25. 8.1
  26. 4.8
  27. 62
  28. 23
  29. 6.3
  30. 7.4
  31. 40
  32. 7.1
  33. 30
  34. 27
  35. 38
  36. 87
  37. 5.5
  38. 22
  39. 76
  40. 92

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