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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 574 · 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.√88 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.5 (d) 9.2
  2. 2.√48 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 6.6 (d) 6.7
  3. 3.√43 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.5 (d) 6.4
  4. 4.Best estimate of 1685 ÷ 23? (a) 840 (b) 8400 (c) 84
  5. 5.Best estimate of 6700 ÷ 79? (a) 84 (b) 8400 (c) 840
  6. 6.Best estimate of 7971 ÷ 86? (a) 890 (b) 89 (c) 8900
  7. 7.Best estimate of 2454 ÷ 28? (a) 82 (b) 820 (c) 8200
  8. 8.√20 to 1 decimal place? (a) 4.7 (b) 4.6 (c) 4.4 (d) 4.5
  9. 9.Best estimate of 2179 ÷ 49? (a) 440 (b) 44 (c) 4400
  10. 10.√34 to 1 decimal place? (a) 5.8 (b) 5.7 (c) 6.0 (d) 5.9
  11. 11.√53 to 1 decimal place? (a) 7.3 (b) 7.6 (c) 7.4 (d) 7.5
  12. 12.√21 to 1 decimal place? (a) 4.8 (b) 4.9 (c) 4.7 (d) 4.6
  13. 13.Best estimate of 4559 ÷ 61? (a) 76 (b) 7600 (c) 760
  14. 14.Best estimate of 1343 ÷ 38? (a) 340 (b) 3400 (c) 34
  15. 15.Best estimate of 2676 ÷ 48? (a) 5400 (b) 540 (c) 54
  16. 16.√61 to 1 decimal place? (a) 7.9 (b) 7.8 (c) 8.0 (d) 7.7
  17. 17.Best estimate of 2850 ÷ 44? (a) 710 (b) 71 (c) 7100
  18. 18.Best estimate of 2381 ÷ 82? (a) 30 (b) 300 (c) 3000
  19. 19.√23 to 1 decimal place? (a) 5.1 (b) 4.9 (c) 5.0 (d) 4.8
  20. 20.Best estimate of 2044 ÷ 84? (a) 26 (b) 2600 (c) 260
  21. 21.Best estimate of 5285 ÷ 66? (a) 7600 (b) 76 (c) 760
  22. 22.√37 to 1 decimal place? (a) 6.3 (b) 6.1 (c) 6.2 (d) 6.0
  23. 23.√72 to 1 decimal place? (a) 8.5 (b) 8.7 (c) 8.4 (d) 8.6
  24. 24.√78 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 8.8 (d) 9.1
  25. 25.√42 to 1 decimal place? (a) 6.6 (b) 6.5 (c) 6.3 (d) 6.4
  26. 26.√50 to 1 decimal place? (a) 7.1 (b) 6.9 (c) 7.2 (d) 7.0
  27. 27.√96 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.8 (d) 9.9
  28. 28.Best estimate of 1329 ÷ 44? (a) 3300 (b) 330 (c) 33
  29. 29.Best estimate of 1369 ÷ 63? (a) 23 (b) 230 (c) 2300
  30. 30.√40 to 1 decimal place? (a) 6.3 (b) 6.1 (c) 6.0 (d) 6.2
  31. 31.Best estimate of 3075 ÷ 46? (a) 62 (b) 6200 (c) 620
  32. 32.Best estimate of 5749 ÷ 86? (a) 6400 (b) 64 (c) 640
  33. 33.√65 to 1 decimal place? (a) 8.2 (b) 7.9 (c) 8.1 (d) 8.0
  34. 34.Best estimate of 5816 ÷ 86? (a) 650 (b) 65 (c) 6500
  35. 35.√87 to 1 decimal place? (a) 9.3 (b) 9.5 (c) 9.6 (d) 9.4
  36. 36.Best estimate of 4376 ÷ 69? (a) 63 (b) 6300 (c) 630
  37. 37.Best estimate of 1125 ÷ 41? (a) 280 (b) 28 (c) 2800
  38. 38.Best estimate of 2169 ÷ 64? (a) 360 (b) 3600 (c) 36
  39. 39.√46 to 1 decimal place? (a) 6.9 (b) 6.6 (c) 6.7 (d) 6.8
  40. 40.Best estimate of 1893 ÷ 27? (a) 6300 (b) 63 (c) 630

Answer key

  1. 9.4
  2. 6.9
  3. 6.6
  4. 84
  5. 84
  6. 89
  7. 82
  8. 4.5
  9. 44
  10. 5.8
  11. 7.3
  12. 4.6
  13. 76
  14. 34
  15. 54
  16. 7.8
  17. 71
  18. 30
  19. 4.8
  20. 26
  21. 76
  22. 6.1
  23. 8.5
  24. 8.8
  25. 6.5
  26. 7.1
  27. 9.8
  28. 33
  29. 23
  30. 6.3
  31. 62
  32. 64
  33. 8.1
  34. 65
  35. 9.3
  36. 63
  37. 28
  38. 36
  39. 6.8
  40. 63

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