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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 392 · 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.√92 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.9 (d) 9.7
  2. 2.Best estimate of 1372 ÷ 36? (a) 3400 (b) 340 (c) 34
  3. 3.Best estimate of 2646 ÷ 36? (a) 660 (b) 6600 (c) 66
  4. 4.Best estimate of 6066 ÷ 69? (a) 8700 (b) 870 (c) 87
  5. 5.√55 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.3 (d) 7.6
  6. 6.√98 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.6 (d) 9.9
  7. 7.√31 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.7 (d) 5.4
  8. 8.Best estimate of 933 ÷ 66? (a) 130 (b) 1300 (c) 13
  9. 9.√67 to 1 decimal place? (a) 8.2 (b) 8.4 (c) 8.5 (d) 8.3
  10. 10.Best estimate of 2222 ÷ 29? (a) 74 (b) 7400 (c) 740
  11. 11.Best estimate of 4412 ÷ 81? (a) 550 (b) 55 (c) 5500
  12. 12.√71 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.4 (d) 8.5
  13. 13.Best estimate of 3529 ÷ 53? (a) 710 (b) 7100 (c) 71
  14. 14.√28 to 1 decimal place? (a) 5.3 (b) 5.4 (c) 5.2 (d) 5.5
  15. 15.√34 to 1 decimal place? (a) 5.7 (b) 5.8 (c) 5.6 (d) 5.5
  16. 16.√46 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.8 (d) 6.5
  17. 17.√79 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 9.1 (d) 8.8
  18. 18.√32 to 1 decimal place? (a) 5.7 (b) 5.9 (c) 5.6 (d) 5.8
  19. 19.Best estimate of 1761 ÷ 46? (a) 3500 (b) 350 (c) 35
  20. 20.Best estimate of 1531 ÷ 38? (a) 3800 (b) 380 (c) 38
  21. 21.Best estimate of 2798 ÷ 32? (a) 930 (b) 9300 (c) 93
  22. 22.√94 to 1 decimal place? (a) 9.7 (b) 9.9 (c) 10.0 (d) 9.8
  23. 23.Best estimate of 429 ÷ 26? (a) 1400 (b) 140 (c) 14
  24. 24.√37 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 6.2 (d) 6.1
  25. 25.Best estimate of 813 ÷ 48? (a) 1600 (b) 16 (c) 160
  26. 26.Best estimate of 776 ÷ 39? (a) 190 (b) 1900 (c) 19
  27. 27.√40 to 1 decimal place? (a) 6.4 (b) 6.5 (c) 6.6 (d) 6.3
  28. 28.√86 to 1 decimal place? (a) 9.6 (b) 9.3 (c) 9.4 (d) 9.5
  29. 29.Best estimate of 2659 ÷ 64? (a) 44 (b) 4400 (c) 440
  30. 30.√50 to 1 decimal place? (a) 7.0 (b) 6.8 (c) 6.9 (d) 7.1
  31. 31.√65 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.1 (d) 8.0
  32. 32.Best estimate of 6787 ÷ 76? (a) 8500 (b) 85 (c) 850
  33. 33.Best estimate of 2265 ÷ 36? (a) 570 (b) 5700 (c) 57
  34. 34.√47 to 1 decimal place? (a) 7.0 (b) 7.2 (c) 7.1 (d) 6.9
  35. 35.Best estimate of 2088 ÷ 67? (a) 300 (b) 3000 (c) 30
  36. 36.Best estimate of 1847 ÷ 67? (a) 260 (b) 2600 (c) 26
  37. 37.√26 to 1 decimal place? (a) 5.1 (b) 5.0 (c) 4.9 (d) 4.8
  38. 38.Best estimate of 899 ÷ 61? (a) 15 (b) 150 (c) 1500
  39. 39.Best estimate of 1372 ÷ 41? (a) 34 (b) 3400 (c) 340
  40. 40.Best estimate of 1399 ÷ 63? (a) 2300 (b) 230 (c) 23

Answer key

  1. 9.6
  2. 34
  3. 66
  4. 87
  5. 7.4
  6. 9.9
  7. 5.6
  8. 13
  9. 8.2
  10. 74
  11. 55
  12. 8.4
  13. 71
  14. 5.3
  15. 5.8
  16. 6.8
  17. 8.9
  18. 5.7
  19. 35
  20. 38
  21. 93
  22. 9.7
  23. 14
  24. 6.1
  25. 16
  26. 19
  27. 6.3
  28. 9.3
  29. 44
  30. 7.1
  31. 8.1
  32. 85
  33. 57
  34. 6.9
  35. 30
  36. 26
  37. 5.1
  38. 15
  39. 34
  40. 23

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