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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 684 · 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 1442 ÷ 62? (a) 24 (b) 240 (c) 2400
  2. 2.√74 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.5 (d) 8.6
  3. 3.Best estimate of 1711 ÷ 33? (a) 570 (b) 5700 (c) 57
  4. 4.Best estimate of 1901 ÷ 27? (a) 6300 (b) 630 (c) 63
  5. 5.√76 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 8.7 (d) 8.6
  6. 6.Best estimate of 1645 ÷ 39? (a) 41 (b) 410 (c) 4100
  7. 7.√32 to 1 decimal place? (a) 5.8 (b) 5.9 (c) 6.0 (d) 5.7
  8. 8.√82 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.1 (d) 9.0
  9. 9.Best estimate of 1811 ÷ 54? (a) 360 (b) 36 (c) 3600
  10. 10.√40 to 1 decimal place? (a) 6.0 (b) 6.2 (c) 6.3 (d) 6.1
  11. 11.Best estimate of 762 ÷ 46? (a) 1500 (b) 150 (c) 15
  12. 12.Best estimate of 4947 ÷ 78? (a) 6200 (b) 620 (c) 62
  13. 13.√94 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.6 (d) 9.9
  14. 14.Best estimate of 6108 ÷ 72? (a) 87 (b) 8700 (c) 870
  15. 15.Best estimate of 7045 ÷ 82? (a) 88 (b) 8800 (c) 880
  16. 16.Best estimate of 1779 ÷ 47? (a) 3600 (b) 360 (c) 36
  17. 17.Best estimate of 1269 ÷ 39? (a) 320 (b) 32 (c) 3200
  18. 18.Best estimate of 1303 ÷ 51? (a) 26 (b) 260 (c) 2600
  19. 19.Best estimate of 4511 ÷ 72? (a) 640 (b) 6400 (c) 64
  20. 20.Best estimate of 2190 ÷ 46? (a) 440 (b) 4400 (c) 44
  21. 21.Best estimate of 3583 ÷ 52? (a) 72 (b) 720 (c) 7200
  22. 22.Best estimate of 1526 ÷ 26? (a) 5100 (b) 510 (c) 51
  23. 23.Best estimate of 556 ÷ 26? (a) 19 (b) 1900 (c) 190
  24. 24.√41 to 1 decimal place? (a) 6.4 (b) 6.5 (c) 6.3 (d) 6.6
  25. 25.√37 to 1 decimal place? (a) 6.1 (b) 6.4 (c) 6.3 (d) 6.2
  26. 26.√98 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 9.7 (d) 10.0
  27. 27.√53 to 1 decimal place? (a) 7.4 (b) 7.6 (c) 7.5 (d) 7.3
  28. 28.Best estimate of 2273 ÷ 32? (a) 760 (b) 7600 (c) 76
  29. 29.Best estimate of 2655 ÷ 33? (a) 89 (b) 8900 (c) 890
  30. 30.Best estimate of 5171 ÷ 62? (a) 8600 (b) 860 (c) 86
  31. 31.Best estimate of 3490 ÷ 38? (a) 87 (b) 8700 (c) 870
  32. 32.Best estimate of 1574 ÷ 47? (a) 31 (b) 3100 (c) 310
  33. 33.√92 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.7 (d) 9.5
  34. 34.Best estimate of 620 ÷ 46? (a) 120 (b) 12 (c) 1200
  35. 35.Best estimate of 7020 ÷ 81? (a) 880 (b) 8800 (c) 88
  36. 36.√70 to 1 decimal place? (a) 8.4 (b) 8.2 (c) 8.3 (d) 8.5
  37. 37.Best estimate of 1615 ÷ 33? (a) 540 (b) 54 (c) 5400
  38. 38.Best estimate of 2643 ÷ 59? (a) 4400 (b) 440 (c) 44
  39. 39.Best estimate of 2005 ÷ 32? (a) 67 (b) 670 (c) 6700
  40. 40.Best estimate of 1550 ÷ 44? (a) 390 (b) 39 (c) 3900

Answer key

  1. 24
  2. 8.6
  3. 57
  4. 63
  5. 8.7
  6. 41
  7. 5.7
  8. 9.1
  9. 36
  10. 6.3
  11. 15
  12. 62
  13. 9.7
  14. 87
  15. 88
  16. 36
  17. 32
  18. 26
  19. 64
  20. 44
  21. 72
  22. 51
  23. 19
  24. 6.4
  25. 6.1
  26. 9.9
  27. 7.3
  28. 76
  29. 89
  30. 86
  31. 87
  32. 31
  33. 9.6
  34. 12
  35. 88
  36. 8.4
  37. 54
  38. 44
  39. 67
  40. 39

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