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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 993 · 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.√23 to 1 decimal place? (a) 5.0 (b) 5.1 (c) 4.9 (d) 4.8
  2. 2.√92 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.4 (d) 9.6
  3. 3.Best estimate of 3850 ÷ 63? (a) 640 (b) 6400 (c) 64
  4. 4.Best estimate of 2588 ÷ 52? (a) 52 (b) 520 (c) 5200
  5. 5.√98 to 1 decimal place? (a) 10.1 (b) 10.0 (c) 9.8 (d) 9.9
  6. 6.Best estimate of 2652 ÷ 66? (a) 3800 (b) 380 (c) 38
  7. 7.√87 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.2 (d) 9.3
  8. 8.Best estimate of 1972 ÷ 74? (a) 2800 (b) 28 (c) 280
  9. 9.Best estimate of 1083 ÷ 22? (a) 540 (b) 5400 (c) 54
  10. 10.√75 to 1 decimal place? (a) 8.8 (b) 8.6 (c) 8.7 (d) 8.5
  11. 11.√96 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 10.0 (d) 10.1
  12. 12.√47 to 1 decimal place? (a) 6.6 (b) 6.9 (c) 6.8 (d) 6.7
  13. 13.√58 to 1 decimal place? (a) 7.5 (b) 7.3 (c) 7.4 (d) 7.6
  14. 14.√37 to 1 decimal place? (a) 6.1 (b) 5.8 (c) 5.9 (d) 6.0
  15. 15.√50 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 7.4 (d) 7.3
  16. 16.Best estimate of 745 ÷ 31? (a) 250 (b) 2500 (c) 25
  17. 17.Best estimate of 2046 ÷ 41? (a) 51 (b) 5100 (c) 510
  18. 18.√62 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 8.2 (d) 8.1
  19. 19.Best estimate of 2792 ÷ 62? (a) 4700 (b) 47 (c) 470
  20. 20.√22 to 1 decimal place? (a) 4.7 (b) 4.4 (c) 4.6 (d) 4.5
  21. 21.Best estimate of 1560 ÷ 34? (a) 52 (b) 520 (c) 5200
  22. 22.√55 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.4 (d) 7.5
  23. 23.Best estimate of 1752 ÷ 22? (a) 88 (b) 8800 (c) 880
  24. 24.Best estimate of 1780 ÷ 88? (a) 200 (b) 2000 (c) 20
  25. 25.Best estimate of 1140 ÷ 52? (a) 230 (b) 2300 (c) 23
  26. 26.√46 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 6.7 (d) 6.6
  27. 27.Best estimate of 5338 ÷ 57? (a) 8900 (b) 890 (c) 89
  28. 28.√32 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.8 (d) 5.5
  29. 29.Best estimate of 1741 ÷ 24? (a) 870 (b) 8700 (c) 87
  30. 30.Best estimate of 1832 ÷ 22? (a) 920 (b) 92 (c) 9200
  31. 31.Best estimate of 2389 ÷ 54? (a) 48 (b) 4800 (c) 480
  32. 32.Best estimate of 1784 ÷ 66? (a) 250 (b) 25 (c) 2500
  33. 33.√52 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.1 (d) 7.2
  34. 34.Best estimate of 1470 ÷ 62? (a) 250 (b) 25 (c) 2500
  35. 35.Best estimate of 1580 ÷ 28? (a) 530 (b) 5300 (c) 53
  36. 36.√41 to 1 decimal place? (a) 6.7 (b) 6.5 (c) 6.6 (d) 6.4
  37. 37.√20 to 1 decimal place? (a) 4.5 (b) 4.8 (c) 4.6 (d) 4.7
  38. 38.Best estimate of 2519 ÷ 39? (a) 63 (b) 630 (c) 6300
  39. 39.Best estimate of 1319 ÷ 46? (a) 2600 (b) 260 (c) 26
  40. 40.√82 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 8.9 (d) 9.0

Answer key

  1. 4.8
  2. 9.6
  3. 64
  4. 52
  5. 9.9
  6. 38
  7. 9.3
  8. 28
  9. 54
  10. 8.7
  11. 9.8
  12. 6.9
  13. 7.6
  14. 6.1
  15. 7.1
  16. 25
  17. 51
  18. 7.9
  19. 47
  20. 4.7
  21. 52
  22. 7.4
  23. 88
  24. 20
  25. 23
  26. 6.8
  27. 89
  28. 5.7
  29. 87
  30. 92
  31. 48
  32. 25
  33. 7.2
  34. 25
  35. 53
  36. 6.4
  37. 4.5
  38. 63
  39. 26
  40. 9.1

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