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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 921 · 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.√74 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.5 (d) 8.6
  2. 2.Best estimate of 2193 ÷ 51? (a) 440 (b) 44 (c) 4400
  3. 3.Best estimate of 1094 ÷ 33? (a) 360 (b) 3600 (c) 36
  4. 4.Best estimate of 3582 ÷ 76? (a) 4500 (b) 45 (c) 450
  5. 5.√69 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 8.3 (d) 8.4
  6. 6.Best estimate of 6443 ÷ 71? (a) 9200 (b) 92 (c) 920
  7. 7.√59 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.6 (d) 7.5
  8. 8.Best estimate of 3121 ÷ 52? (a) 6200 (b) 620 (c) 62
  9. 9.Best estimate of 1424 ÷ 27? (a) 4700 (b) 470 (c) 47
  10. 10.√21 to 1 decimal place? (a) 4.8 (b) 4.5 (c) 4.6 (d) 4.7
  11. 11.Best estimate of 3784 ÷ 51? (a) 760 (b) 7600 (c) 76
  12. 12.√96 to 1 decimal place? (a) 10.1 (b) 9.9 (c) 10.0 (d) 9.8
  13. 13.Best estimate of 5433 ÷ 62? (a) 9100 (b) 910 (c) 91
  14. 14.Best estimate of 2242 ÷ 46? (a) 450 (b) 4500 (c) 45
  15. 15.√43 to 1 decimal place? (a) 6.6 (b) 6.4 (c) 6.3 (d) 6.5
  16. 16.Best estimate of 1874 ÷ 88? (a) 2100 (b) 21 (c) 210
  17. 17.√79 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 8.9 (d) 8.8
  18. 18.√42 to 1 decimal place? (a) 6.4 (b) 6.5 (c) 6.6 (d) 6.3
  19. 19.√27 to 1 decimal place? (a) 5.3 (b) 5.2 (c) 5.1 (d) 5.0
  20. 20.√83 to 1 decimal place? (a) 9.0 (b) 8.8 (c) 8.9 (d) 9.1
  21. 21.√20 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.8 (d) 4.5
  22. 22.√31 to 1 decimal place? (a) 5.5 (b) 5.3 (c) 5.6 (d) 5.4
  23. 23.Best estimate of 1575 ÷ 39? (a) 390 (b) 39 (c) 3900
  24. 24.√77 to 1 decimal place? (a) 9.1 (b) 8.8 (c) 9.0 (d) 8.9
  25. 25.√58 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.6 (d) 7.3
  26. 26.√94 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.4 (d) 9.5
  27. 27.√62 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 7.7 (d) 7.6
  28. 28.Best estimate of 339 ÷ 26? (a) 11 (b) 1100 (c) 110
  29. 29.Best estimate of 1821 ÷ 22? (a) 910 (b) 9100 (c) 91
  30. 30.Best estimate of 7237 ÷ 76? (a) 9000 (b) 900 (c) 90
  31. 31.Best estimate of 1339 ÷ 23? (a) 67 (b) 670 (c) 6700
  32. 32.Best estimate of 1530 ÷ 37? (a) 380 (b) 38 (c) 3800
  33. 33.√61 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 8.0 (d) 8.1
  34. 34.√51 to 1 decimal place? (a) 6.9 (b) 7.0 (c) 6.8 (d) 7.1
  35. 35.√23 to 1 decimal place? (a) 4.9 (b) 4.7 (c) 4.8 (d) 5.0
  36. 36.Best estimate of 2492 ÷ 43? (a) 620 (b) 62 (c) 6200
  37. 37.√53 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.1 (d) 7.0
  38. 38.√92 to 1 decimal place? (a) 9.4 (b) 9.7 (c) 9.6 (d) 9.5
  39. 39.√67 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 8.3 (d) 8.0
  40. 40.Best estimate of 3548 ÷ 53? (a) 710 (b) 7100 (c) 71

Answer key

  1. 8.6
  2. 44
  3. 36
  4. 45
  5. 8.3
  6. 92
  7. 7.7
  8. 62
  9. 47
  10. 4.6
  11. 76
  12. 9.8
  13. 91
  14. 45
  15. 6.6
  16. 21
  17. 8.9
  18. 6.5
  19. 5.2
  20. 9.1
  21. 4.5
  22. 5.6
  23. 39
  24. 8.8
  25. 7.6
  26. 9.7
  27. 7.9
  28. 11
  29. 91
  30. 90
  31. 67
  32. 38
  33. 7.8
  34. 7.1
  35. 4.8
  36. 62
  37. 7.3
  38. 9.6
  39. 8.2
  40. 71

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