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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 894 · 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 5060 ÷ 79? (a) 630 (b) 63 (c) 6300
  2. 2.√32 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.5 (d) 5.4
  3. 3.Best estimate of 1906 ÷ 82? (a) 24 (b) 240 (c) 2400
  4. 4.√78 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.9 (d) 8.6
  5. 5.Best estimate of 1015 ÷ 26? (a) 3400 (b) 34 (c) 340
  6. 6.Best estimate of 4344 ÷ 83? (a) 540 (b) 54 (c) 5400
  7. 7.√72 to 1 decimal place? (a) 8.8 (b) 8.5 (c) 8.7 (d) 8.6
  8. 8.Best estimate of 1594 ÷ 46? (a) 3200 (b) 32 (c) 320
  9. 9.Best estimate of 321 ÷ 26? (a) 11 (b) 1100 (c) 110
  10. 10.Best estimate of 4955 ÷ 86? (a) 55 (b) 550 (c) 5500
  11. 11.√26 to 1 decimal place? (a) 5.1 (b) 5.3 (c) 5.4 (d) 5.2
  12. 12.√61 to 1 decimal place? (a) 7.7 (b) 7.5 (c) 7.6 (d) 7.8
  13. 13.√83 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 8.8 (d) 8.9
  14. 14.√80 to 1 decimal place? (a) 9.1 (b) 8.8 (c) 9.0 (d) 8.9
  15. 15.Best estimate of 1113 ÷ 49? (a) 220 (b) 22 (c) 2200
  16. 16.√92 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.8 (d) 9.7
  17. 17.√55 to 1 decimal place? (a) 7.5 (b) 7.7 (c) 7.6 (d) 7.4
  18. 18.Best estimate of 7576 ÷ 89? (a) 8400 (b) 840 (c) 84
  19. 19.Best estimate of 2952 ÷ 44? (a) 74 (b) 740 (c) 7400
  20. 20.Best estimate of 4841 ÷ 57? (a) 8100 (b) 81 (c) 810
  21. 21.Best estimate of 2391 ÷ 69? (a) 3400 (b) 34 (c) 340
  22. 22.Best estimate of 6472 ÷ 81? (a) 8100 (b) 81 (c) 810
  23. 23.Best estimate of 2248 ÷ 54? (a) 450 (b) 4500 (c) 45
  24. 24.Best estimate of 4001 ÷ 83? (a) 50 (b) 5000 (c) 500
  25. 25.Best estimate of 4497 ÷ 84? (a) 560 (b) 5600 (c) 56
  26. 26.√27 to 1 decimal place? (a) 5.1 (b) 5.2 (c) 4.9 (d) 5.0
  27. 27.Best estimate of 8039 ÷ 88? (a) 890 (b) 8900 (c) 89
  28. 28.√71 to 1 decimal place? (a) 8.3 (b) 8.6 (c) 8.4 (d) 8.5
  29. 29.√70 to 1 decimal place? (a) 8.5 (b) 8.3 (c) 8.4 (d) 8.6
  30. 30.Best estimate of 3853 ÷ 71? (a) 550 (b) 55 (c) 5500
  31. 31.Best estimate of 1380 ÷ 69? (a) 2000 (b) 200 (c) 20
  32. 32.√94 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.7 (d) 9.9
  33. 33.√22 to 1 decimal place? (a) 4.7 (b) 4.9 (c) 4.8 (d) 5.0
  34. 34.√21 to 1 decimal place? (a) 4.6 (b) 4.5 (c) 4.4 (d) 4.3
  35. 35.√58 to 1 decimal place? (a) 7.5 (b) 7.7 (c) 7.6 (d) 7.8
  36. 36.Best estimate of 6819 ÷ 76? (a) 8500 (b) 85 (c) 850
  37. 37.Best estimate of 1140 ÷ 21? (a) 57 (b) 5700 (c) 570
  38. 38.√69 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.4 (d) 8.3
  39. 39.Best estimate of 1131 ÷ 89? (a) 13 (b) 130 (c) 1300
  40. 40.√29 to 1 decimal place? (a) 5.3 (b) 5.4 (c) 5.6 (d) 5.5

Answer key

  1. 63
  2. 5.7
  3. 24
  4. 8.8
  5. 34
  6. 54
  7. 8.5
  8. 32
  9. 11
  10. 55
  11. 5.1
  12. 7.8
  13. 9.1
  14. 8.9
  15. 22
  16. 9.6
  17. 7.4
  18. 84
  19. 74
  20. 81
  21. 34
  22. 81
  23. 45
  24. 50
  25. 56
  26. 5.2
  27. 89
  28. 8.4
  29. 8.4
  30. 55
  31. 20
  32. 9.7
  33. 4.7
  34. 4.6
  35. 7.6
  36. 85
  37. 57
  38. 8.3
  39. 13
  40. 5.4

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