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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 996 · 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 1789 ÷ 26? (a) 6000 (b) 600 (c) 60
  2. 2.Best estimate of 2370 ÷ 82? (a) 300 (b) 30 (c) 3000
  3. 3.√71 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.5 (d) 8.3
  4. 4.Best estimate of 1373 ÷ 73? (a) 2000 (b) 200 (c) 20
  5. 5.√79 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 9.2 (d) 8.9
  6. 6.√98 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 10.0 (d) 9.9
  7. 7.√29 to 1 decimal place? (a) 5.3 (b) 5.4 (c) 5.1 (d) 5.2
  8. 8.√28 to 1 decimal place? (a) 5.0 (b) 5.3 (c) 5.1 (d) 5.2
  9. 9.Best estimate of 940 ÷ 71? (a) 1300 (b) 13 (c) 130
  10. 10.√90 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.8 (d) 9.7
  11. 11.Best estimate of 5599 ÷ 86? (a) 6200 (b) 620 (c) 62
  12. 12.Best estimate of 1589 ÷ 36? (a) 40 (b) 4000 (c) 400
  13. 13.Best estimate of 2359 ÷ 89? (a) 2600 (b) 260 (c) 26
  14. 14.√26 to 1 decimal place? (a) 5.0 (b) 5.1 (c) 4.8 (d) 4.9
  15. 15.Best estimate of 3976 ÷ 74? (a) 570 (b) 5700 (c) 57
  16. 16.√78 to 1 decimal place? (a) 8.8 (b) 8.6 (c) 8.7 (d) 8.9
  17. 17.Best estimate of 2117 ÷ 81? (a) 26 (b) 2600 (c) 260
  18. 18.√62 to 1 decimal place? (a) 7.9 (b) 7.7 (c) 8.0 (d) 7.8
  19. 19.Best estimate of 1832 ÷ 22? (a) 9200 (b) 920 (c) 92
  20. 20.√94 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 10.0 (d) 9.9
  21. 21.Best estimate of 6964 ÷ 79? (a) 870 (b) 8700 (c) 87
  22. 22.Best estimate of 1062 ÷ 33? (a) 3500 (b) 35 (c) 350
  23. 23.Best estimate of 2270 ÷ 77? (a) 280 (b) 2800 (c) 28
  24. 24.Best estimate of 3836 ÷ 41? (a) 9600 (b) 960 (c) 96
  25. 25.√84 to 1 decimal place? (a) 9.2 (b) 9.0 (c) 9.1 (d) 8.9
  26. 26.Best estimate of 2449 ÷ 29? (a) 820 (b) 8200 (c) 82
  27. 27.Best estimate of 1484 ÷ 24? (a) 74 (b) 7400 (c) 740
  28. 28.Best estimate of 3212 ÷ 56? (a) 54 (b) 5400 (c) 540
  29. 29.Best estimate of 2038 ÷ 64? (a) 340 (b) 34 (c) 3400
  30. 30.Best estimate of 1668 ÷ 21? (a) 830 (b) 83 (c) 8300
  31. 31.Best estimate of 2993 ÷ 52? (a) 600 (b) 6000 (c) 60
  32. 32.Best estimate of 1548 ÷ 63? (a) 260 (b) 2600 (c) 26
  33. 33.Best estimate of 1939 ÷ 62? (a) 32 (b) 3200 (c) 320
  34. 34.√92 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.8 (d) 9.7
  35. 35.√67 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 8.2 (d) 8.1
  36. 36.Best estimate of 777 ÷ 48? (a) 160 (b) 1600 (c) 16
  37. 37.Best estimate of 919 ÷ 42? (a) 230 (b) 23 (c) 2300
  38. 38.√80 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 9.1 (d) 8.8
  39. 39.√23 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 4.8 (d) 5.1
  40. 40.Best estimate of 7085 ÷ 77? (a) 8900 (b) 890 (c) 89

Answer key

  1. 60
  2. 30
  3. 8.4
  4. 20
  5. 8.9
  6. 9.9
  7. 5.4
  8. 5.3
  9. 13
  10. 9.5
  11. 62
  12. 40
  13. 26
  14. 5.1
  15. 57
  16. 8.8
  17. 26
  18. 7.9
  19. 92
  20. 9.7
  21. 87
  22. 35
  23. 28
  24. 96
  25. 9.2
  26. 82
  27. 74
  28. 54
  29. 34
  30. 83
  31. 60
  32. 26
  33. 32
  34. 9.6
  35. 8.2
  36. 16
  37. 23
  38. 8.9
  39. 4.8
  40. 89

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