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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 728 · 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 674 ÷ 26? (a) 2200 (b) 22 (c) 220
  2. 2.Best estimate of 944 ÷ 42? (a) 2400 (b) 240 (c) 24
  3. 3.Best estimate of 750 ÷ 42? (a) 1900 (b) 19 (c) 190
  4. 4.√45 to 1 decimal place? (a) 6.9 (b) 7.0 (c) 6.8 (d) 6.7
  5. 5.√92 to 1 decimal place? (a) 9.6 (b) 9.4 (c) 9.7 (d) 9.5
  6. 6.Best estimate of 1376 ÷ 54? (a) 280 (b) 2800 (c) 28
  7. 7.√52 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.1 (d) 7.0
  8. 8.Best estimate of 2928 ÷ 46? (a) 590 (b) 5900 (c) 59
  9. 9.Best estimate of 3067 ÷ 37? (a) 77 (b) 7700 (c) 770
  10. 10.Best estimate of 1009 ÷ 32? (a) 3400 (b) 34 (c) 340
  11. 11.Best estimate of 5513 ÷ 87? (a) 610 (b) 61 (c) 6100
  12. 12.Best estimate of 1738 ÷ 34? (a) 5800 (b) 58 (c) 580
  13. 13.Best estimate of 5651 ÷ 68? (a) 81 (b) 810 (c) 8100
  14. 14.Best estimate of 1764 ÷ 53? (a) 3500 (b) 35 (c) 350
  15. 15.√20 to 1 decimal place? (a) 4.7 (b) 4.8 (c) 4.6 (d) 4.5
  16. 16.Best estimate of 1975 ÷ 39? (a) 490 (b) 49 (c) 4900
  17. 17.√76 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.5 (d) 8.8
  18. 18.√61 to 1 decimal place? (a) 7.9 (b) 7.7 (c) 7.8 (d) 7.6
  19. 19.Best estimate of 2428 ÷ 82? (a) 30 (b) 300 (c) 3000
  20. 20.√26 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 5.1 (d) 4.8
  21. 21.√30 to 1 decimal place? (a) 5.4 (b) 5.5 (c) 5.6 (d) 5.7
  22. 22.Best estimate of 2158 ÷ 29? (a) 7200 (b) 72 (c) 720
  23. 23.Best estimate of 7536 ÷ 81? (a) 940 (b) 94 (c) 9400
  24. 24.Best estimate of 1551 ÷ 56? (a) 260 (b) 2600 (c) 26
  25. 25.√82 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 9.1 (d) 9.2
  26. 26.Best estimate of 4174 ÷ 63? (a) 70 (b) 700 (c) 7000
  27. 27.Best estimate of 4010 ÷ 87? (a) 450 (b) 4500 (c) 45
  28. 28.Best estimate of 1327 ÷ 31? (a) 440 (b) 4400 (c) 44
  29. 29.Best estimate of 1404 ÷ 26? (a) 47 (b) 4700 (c) 470
  30. 30.√74 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.7 (d) 8.8
  31. 31.Best estimate of 4136 ÷ 52? (a) 8300 (b) 830 (c) 83
  32. 32.Best estimate of 5949 ÷ 86? (a) 66 (b) 6600 (c) 660
  33. 33.Best estimate of 1716 ÷ 87? (a) 19 (b) 190 (c) 1900
  34. 34.√23 to 1 decimal place? (a) 4.9 (b) 5.0 (c) 4.7 (d) 4.8
  35. 35.√69 to 1 decimal place? (a) 8.0 (b) 8.3 (c) 8.2 (d) 8.1
  36. 36.Best estimate of 4955 ÷ 53? (a) 9900 (b) 990 (c) 99
  37. 37.Best estimate of 1353 ÷ 27? (a) 45 (b) 450 (c) 4500
  38. 38.Best estimate of 674 ÷ 24? (a) 3400 (b) 340 (c) 34
  39. 39.Best estimate of 2305 ÷ 34? (a) 7700 (b) 770 (c) 77
  40. 40.Best estimate of 2413 ÷ 59? (a) 40 (b) 4000 (c) 400

Answer key

  1. 22
  2. 24
  3. 19
  4. 6.7
  5. 9.6
  6. 28
  7. 7.2
  8. 59
  9. 77
  10. 34
  11. 61
  12. 58
  13. 81
  14. 35
  15. 4.5
  16. 49
  17. 8.7
  18. 7.8
  19. 30
  20. 5.1
  21. 5.5
  22. 72
  23. 94
  24. 26
  25. 9.1
  26. 70
  27. 45
  28. 44
  29. 47
  30. 8.6
  31. 83
  32. 66
  33. 19
  34. 4.8
  35. 8.3
  36. 99
  37. 45
  38. 34
  39. 77
  40. 40

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