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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 663 · 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.√77 to 1 decimal place? (a) 8.8 (b) 8.6 (c) 8.5 (d) 8.7
  2. 2.Best estimate of 1621 ÷ 52? (a) 32 (b) 320 (c) 3200
  3. 3.Best estimate of 2790 ÷ 49? (a) 560 (b) 5600 (c) 56
  4. 4.√53 to 1 decimal place? (a) 7.3 (b) 7.1 (c) 7.0 (d) 7.2
  5. 5.Best estimate of 1201 ÷ 48? (a) 2400 (b) 24 (c) 240
  6. 6.√72 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.3 (d) 8.5
  7. 7.Best estimate of 3425 ÷ 62? (a) 5700 (b) 57 (c) 570
  8. 8.√87 to 1 decimal place? (a) 9.3 (b) 9.1 (c) 9.4 (d) 9.2
  9. 9.Best estimate of 4667 ÷ 51? (a) 930 (b) 93 (c) 9300
  10. 10.Best estimate of 1368 ÷ 56? (a) 230 (b) 23 (c) 2300
  11. 11.Best estimate of 3786 ÷ 83? (a) 470 (b) 47 (c) 4700
  12. 12.√61 to 1 decimal place? (a) 7.8 (b) 7.6 (c) 7.5 (d) 7.7
  13. 13.√47 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 6.7 (d) 7.0
  14. 14.Best estimate of 644 ÷ 46? (a) 130 (b) 1300 (c) 13
  15. 15.Best estimate of 6232 ÷ 83? (a) 780 (b) 7800 (c) 78
  16. 16.Best estimate of 3812 ÷ 49? (a) 7600 (b) 760 (c) 76
  17. 17.Best estimate of 6260 ÷ 78? (a) 780 (b) 7800 (c) 78
  18. 18.Best estimate of 1770 ÷ 36? (a) 4400 (b) 440 (c) 44
  19. 19.√35 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 5.7 (d) 5.8
  20. 20.√71 to 1 decimal place? (a) 8.3 (b) 8.5 (c) 8.4 (d) 8.2
  21. 21.√74 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 8.7 (d) 8.6
  22. 22.√59 to 1 decimal place? (a) 7.8 (b) 7.6 (c) 7.7 (d) 7.5
  23. 23.Best estimate of 3738 ÷ 62? (a) 6200 (b) 62 (c) 620
  24. 24.Best estimate of 951 ÷ 43? (a) 240 (b) 2400 (c) 24
  25. 25.√46 to 1 decimal place? (a) 7.1 (b) 7.0 (c) 6.8 (d) 6.9
  26. 26.Best estimate of 1571 ÷ 24? (a) 790 (b) 7900 (c) 79
  27. 27.√38 to 1 decimal place? (a) 6.3 (b) 6.2 (c) 6.1 (d) 6.0
  28. 28.Best estimate of 2157 ÷ 41? (a) 54 (b) 540 (c) 5400
  29. 29.Best estimate of 1388 ÷ 28? (a) 46 (b) 460 (c) 4600
  30. 30.Best estimate of 2424 ÷ 36? (a) 6100 (b) 610 (c) 61
  31. 31.Best estimate of 1896 ÷ 58? (a) 320 (b) 32 (c) 3200
  32. 32.Best estimate of 1899 ÷ 21? (a) 950 (b) 95 (c) 9500
  33. 33.Best estimate of 4070 ÷ 82? (a) 510 (b) 5100 (c) 51
  34. 34.Best estimate of 511 ÷ 37? (a) 1300 (b) 130 (c) 13
  35. 35.Best estimate of 3777 ÷ 68? (a) 54 (b) 5400 (c) 540
  36. 36.√78 to 1 decimal place? (a) 8.9 (b) 8.6 (c) 8.8 (d) 8.7
  37. 37.√92 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.6 (d) 9.3
  38. 38.√23 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.8 (d) 4.5
  39. 39.√82 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 8.9 (d) 8.8
  40. 40.√27 to 1 decimal place? (a) 5.1 (b) 5.2 (c) 5.3 (d) 5.4

Answer key

  1. 8.8
  2. 32
  3. 56
  4. 7.3
  5. 24
  6. 8.5
  7. 57
  8. 9.3
  9. 93
  10. 23
  11. 47
  12. 7.8
  13. 6.9
  14. 13
  15. 78
  16. 76
  17. 78
  18. 44
  19. 5.9
  20. 8.4
  21. 8.6
  22. 7.7
  23. 62
  24. 24
  25. 6.8
  26. 79
  27. 6.2
  28. 54
  29. 46
  30. 61
  31. 32
  32. 95
  33. 51
  34. 13
  35. 54
  36. 8.8
  37. 9.6
  38. 4.8
  39. 9.1
  40. 5.2

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