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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 929 · 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.√34 to 1 decimal place? (a) 6.0 (b) 5.8 (c) 5.9 (d) 6.1
  2. 2.Best estimate of 771 ÷ 39? (a) 1900 (b) 19 (c) 190
  3. 3.√85 to 1 decimal place? (a) 9.2 (b) 9.5 (c) 9.3 (d) 9.4
  4. 4.√28 to 1 decimal place? (a) 5.5 (b) 5.3 (c) 5.6 (d) 5.4
  5. 5.√52 to 1 decimal place? (a) 7.2 (b) 7.5 (c) 7.4 (d) 7.3
  6. 6.√20 to 1 decimal place? (a) 4.3 (b) 4.6 (c) 4.4 (d) 4.5
  7. 7.Best estimate of 4562 ÷ 56? (a) 760 (b) 7600 (c) 76
  8. 8.√76 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 8.7 (d) 9.0
  9. 9.Best estimate of 5468 ÷ 64? (a) 9100 (b) 910 (c) 91
  10. 10.Best estimate of 3100 ÷ 36? (a) 78 (b) 780 (c) 7800
  11. 11.Best estimate of 2457 ÷ 33? (a) 82 (b) 8200 (c) 820
  12. 12.Best estimate of 5328 ÷ 58? (a) 890 (b) 8900 (c) 89
  13. 13.√26 to 1 decimal place? (a) 4.8 (b) 5.0 (c) 5.1 (d) 4.9
  14. 14.√71 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.2 (d) 8.5
  15. 15.√61 to 1 decimal place? (a) 7.8 (b) 8.0 (c) 7.9 (d) 7.7
  16. 16.√47 to 1 decimal place? (a) 6.9 (b) 7.0 (c) 7.1 (d) 6.8
  17. 17.Best estimate of 1962 ÷ 63? (a) 33 (b) 3300 (c) 330
  18. 18.Best estimate of 2697 ÷ 43? (a) 67 (b) 6700 (c) 670
  19. 19.Best estimate of 1044 ÷ 29? (a) 350 (b) 3500 (c) 35
  20. 20.√69 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 8.3 (d) 8.2
  21. 21.Best estimate of 2033 ÷ 69? (a) 2900 (b) 290 (c) 29
  22. 22.Best estimate of 2859 ÷ 56? (a) 4800 (b) 480 (c) 48
  23. 23.√56 to 1 decimal place? (a) 7.6 (b) 7.5 (c) 7.7 (d) 7.8
  24. 24.Best estimate of 2435 ÷ 59? (a) 410 (b) 41 (c) 4100
  25. 25.Best estimate of 2964 ÷ 41? (a) 740 (b) 74 (c) 7400
  26. 26.√40 to 1 decimal place? (a) 6.4 (b) 6.5 (c) 6.3 (d) 6.2
  27. 27.√44 to 1 decimal place? (a) 6.6 (b) 6.9 (c) 6.7 (d) 6.8
  28. 28.Best estimate of 630 ÷ 21? (a) 320 (b) 32 (c) 3200
  29. 29.√79 to 1 decimal place? (a) 9.0 (b) 8.8 (c) 8.9 (d) 8.7
  30. 30.√42 to 1 decimal place? (a) 6.4 (b) 6.5 (c) 6.3 (d) 6.6
  31. 31.Best estimate of 4493 ÷ 62? (a) 75 (b) 750 (c) 7500
  32. 32.√74 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.5 (d) 8.4
  33. 33.Best estimate of 2440 ÷ 28? (a) 81 (b) 8100 (c) 810
  34. 34.Best estimate of 4043 ÷ 68? (a) 580 (b) 58 (c) 5800
  35. 35.√67 to 1 decimal place? (a) 8.1 (b) 8.3 (c) 8.0 (d) 8.2
  36. 36.√32 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.4 (d) 5.5
  37. 37.Best estimate of 1343 ÷ 41? (a) 340 (b) 34 (c) 3400
  38. 38.Best estimate of 1422 ÷ 26? (a) 4700 (b) 47 (c) 470
  39. 39.√55 to 1 decimal place? (a) 7.7 (b) 7.5 (c) 7.6 (d) 7.4
  40. 40.Best estimate of 994 ÷ 68? (a) 140 (b) 1400 (c) 14

Answer key

  1. 5.8
  2. 19
  3. 9.2
  4. 5.3
  5. 7.2
  6. 4.5
  7. 76
  8. 8.7
  9. 91
  10. 78
  11. 82
  12. 89
  13. 5.1
  14. 8.4
  15. 7.8
  16. 6.9
  17. 33
  18. 67
  19. 35
  20. 8.3
  21. 29
  22. 48
  23. 7.5
  24. 41
  25. 74
  26. 6.3
  27. 6.6
  28. 32
  29. 8.9
  30. 6.5
  31. 75
  32. 8.6
  33. 81
  34. 58
  35. 8.2
  36. 5.7
  37. 34
  38. 47
  39. 7.4
  40. 14

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