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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 432 · 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.√74 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.5 (d) 8.7
  2. 2.Best estimate of 1996 ÷ 29? (a) 6700 (b) 67 (c) 670
  3. 3.√38 to 1 decimal place? (a) 6.4 (b) 6.1 (c) 6.2 (d) 6.3
  4. 4.√83 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 9.0 (d) 9.1
  5. 5.√34 to 1 decimal place? (a) 5.8 (b) 5.6 (c) 5.7 (d) 5.5
  6. 6.Best estimate of 4772 ÷ 71? (a) 6800 (b) 680 (c) 68
  7. 7.Best estimate of 5296 ÷ 86? (a) 59 (b) 590 (c) 5900
  8. 8.Best estimate of 2902 ÷ 86? (a) 3200 (b) 320 (c) 32
  9. 9.Best estimate of 2485 ÷ 26? (a) 830 (b) 83 (c) 8300
  10. 10.√96 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.9 (d) 9.6
  11. 11.Best estimate of 1330 ÷ 42? (a) 33 (b) 3300 (c) 330
  12. 12.Best estimate of 1153 ÷ 82? (a) 140 (b) 1400 (c) 14
  13. 13.√55 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.5 (d) 7.3
  14. 14.Best estimate of 1517 ÷ 38? (a) 3800 (b) 38 (c) 380
  15. 15.Best estimate of 1097 ÷ 89? (a) 1200 (b) 120 (c) 12
  16. 16.√37 to 1 decimal place? (a) 6.2 (b) 6.0 (c) 6.1 (d) 5.9
  17. 17.√51 to 1 decimal place? (a) 7.4 (b) 7.1 (c) 7.2 (d) 7.3
  18. 18.√40 to 1 decimal place? (a) 6.5 (b) 6.2 (c) 6.4 (d) 6.3
  19. 19.Best estimate of 1244 ÷ 21? (a) 620 (b) 6200 (c) 62
  20. 20.√42 to 1 decimal place? (a) 6.3 (b) 6.5 (c) 6.6 (d) 6.4
  21. 21.Best estimate of 3348 ÷ 36? (a) 840 (b) 8400 (c) 84
  22. 22.Best estimate of 1930 ÷ 46? (a) 390 (b) 3900 (c) 39
  23. 23.√67 to 1 decimal place? (a) 8.5 (b) 8.4 (c) 8.2 (d) 8.3
  24. 24.Best estimate of 982 ÷ 81? (a) 1200 (b) 120 (c) 12
  25. 25.Best estimate of 2809 ÷ 36? (a) 700 (b) 7000 (c) 70
  26. 26.√92 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.7 (d) 9.8
  27. 27.Best estimate of 2934 ÷ 38? (a) 7300 (b) 73 (c) 730
  28. 28.Best estimate of 2977 ÷ 32? (a) 9900 (b) 99 (c) 990
  29. 29.Best estimate of 2073 ÷ 39? (a) 520 (b) 5200 (c) 52
  30. 30.Best estimate of 6424 ÷ 82? (a) 80 (b) 8000 (c) 800
  31. 31.√65 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.1 (d) 8.2
  32. 32.Best estimate of 2616 ÷ 84? (a) 330 (b) 33 (c) 3300
  33. 33.Best estimate of 4614 ÷ 82? (a) 58 (b) 5800 (c) 580
  34. 34.√70 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.5 (d) 8.6
  35. 35.√21 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 4.6 (d) 4.9
  36. 36.Best estimate of 2093 ÷ 52? (a) 420 (b) 42 (c) 4200
  37. 37.Best estimate of 2678 ÷ 28? (a) 890 (b) 8900 (c) 89
  38. 38.√20 to 1 decimal place? (a) 4.7 (b) 4.8 (c) 4.6 (d) 4.5
  39. 39.Best estimate of 1175 ÷ 21? (a) 590 (b) 59 (c) 5900
  40. 40.√41 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.4 (d) 6.5

Answer key

  1. 8.6
  2. 67
  3. 6.2
  4. 9.1
  5. 5.8
  6. 68
  7. 59
  8. 32
  9. 83
  10. 9.8
  11. 33
  12. 14
  13. 7.4
  14. 38
  15. 12
  16. 6.1
  17. 7.1
  18. 6.3
  19. 62
  20. 6.5
  21. 84
  22. 39
  23. 8.2
  24. 12
  25. 70
  26. 9.6
  27. 73
  28. 99
  29. 52
  30. 80
  31. 8.1
  32. 33
  33. 58
  34. 8.4
  35. 4.6
  36. 42
  37. 89
  38. 4.5
  39. 59
  40. 6.4

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