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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 847 · 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 2066 ÷ 46? (a) 4100 (b) 410 (c) 41
  2. 2.Best estimate of 4090 ÷ 83? (a) 51 (b) 510 (c) 5100
  3. 3.Best estimate of 4237 ÷ 81? (a) 530 (b) 53 (c) 5300
  4. 4.Best estimate of 2137 ÷ 37? (a) 530 (b) 5300 (c) 53
  5. 5.√61 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 7.6 (d) 7.7
  6. 6.Best estimate of 1910 ÷ 29? (a) 64 (b) 6400 (c) 640
  7. 7.√37 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 6.1 (d) 5.8
  8. 8.√98 to 1 decimal place? (a) 10.2 (b) 10.0 (c) 10.1 (d) 9.9
  9. 9.Best estimate of 1316 ÷ 28? (a) 44 (b) 4400 (c) 440
  10. 10.√31 to 1 decimal place? (a) 5.6 (b) 5.4 (c) 5.5 (d) 5.7
  11. 11.√65 to 1 decimal place? (a) 8.1 (b) 8.4 (c) 8.3 (d) 8.2
  12. 12.√51 to 1 decimal place? (a) 7.1 (b) 7.0 (c) 7.2 (d) 7.3
  13. 13.Best estimate of 1403 ÷ 37? (a) 350 (b) 3500 (c) 35
  14. 14.Best estimate of 3156 ÷ 62? (a) 530 (b) 53 (c) 5300
  15. 15.Best estimate of 2312 ÷ 56? (a) 3900 (b) 39 (c) 390
  16. 16.√85 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.2 (d) 9.3
  17. 17.√34 to 1 decimal place? (a) 6.0 (b) 5.7 (c) 5.9 (d) 5.8
  18. 18.√45 to 1 decimal place? (a) 6.9 (b) 6.7 (c) 6.8 (d) 7.0
  19. 19.Best estimate of 1651 ÷ 88? (a) 180 (b) 1800 (c) 18
  20. 20.Best estimate of 5938 ÷ 79? (a) 74 (b) 740 (c) 7400
  21. 21.Best estimate of 3646 ÷ 43? (a) 910 (b) 91 (c) 9100
  22. 22.Best estimate of 3353 ÷ 41? (a) 8400 (b) 840 (c) 84
  23. 23.Best estimate of 3204 ÷ 41? (a) 800 (b) 8000 (c) 80
  24. 24.Best estimate of 1171 ÷ 74? (a) 1700 (b) 170 (c) 17
  25. 25.√58 to 1 decimal place? (a) 7.8 (b) 7.6 (c) 7.5 (d) 7.7
  26. 26.Best estimate of 7548 ÷ 82? (a) 94 (b) 940 (c) 9400
  27. 27.Best estimate of 2001 ÷ 78? (a) 250 (b) 2500 (c) 25
  28. 28.√82 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.2 (d) 9.1
  29. 29.Best estimate of 3392 ÷ 58? (a) 570 (b) 5700 (c) 57
  30. 30.√28 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.4 (d) 5.3
  31. 31.Best estimate of 1078 ÷ 29? (a) 3600 (b) 360 (c) 36
  32. 32.√26 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.1 (d) 5.2
  33. 33.Best estimate of 836 ÷ 63? (a) 140 (b) 14 (c) 1400
  34. 34.√74 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.8 (d) 8.5
  35. 35.√70 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.2 (d) 8.1
  36. 36.Best estimate of 1208 ÷ 22? (a) 60 (b) 6000 (c) 600
  37. 37.Best estimate of 2654 ÷ 73? (a) 38 (b) 380 (c) 3800
  38. 38.Best estimate of 5276 ÷ 63? (a) 880 (b) 8800 (c) 88
  39. 39.Best estimate of 3448 ÷ 62? (a) 5700 (b) 570 (c) 57
  40. 40.Best estimate of 3011 ÷ 37? (a) 7500 (b) 75 (c) 750

Answer key

  1. 41
  2. 51
  3. 53
  4. 53
  5. 7.8
  6. 64
  7. 6.1
  8. 9.9
  9. 44
  10. 5.6
  11. 8.1
  12. 7.1
  13. 35
  14. 53
  15. 39
  16. 9.2
  17. 5.8
  18. 6.7
  19. 18
  20. 74
  21. 91
  22. 84
  23. 80
  24. 17
  25. 7.6
  26. 94
  27. 25
  28. 9.1
  29. 57
  30. 5.3
  31. 36
  32. 5.1
  33. 14
  34. 8.6
  35. 8.4
  36. 60
  37. 38
  38. 88
  39. 57
  40. 75

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