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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 79 · 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.√38 to 1 decimal place? (a) 6.2 (b) 6.4 (c) 6.3 (d) 6.5
  2. 2.√72 to 1 decimal place? (a) 8.5 (b) 8.4 (c) 8.6 (d) 8.7
  3. 3.√58 to 1 decimal place? (a) 7.5 (b) 7.8 (c) 7.6 (d) 7.7
  4. 4.√61 to 1 decimal place? (a) 7.6 (b) 7.8 (c) 7.5 (d) 7.7
  5. 5.Best estimate of 1826 ÷ 36? (a) 4600 (b) 460 (c) 46
  6. 6.Best estimate of 4581 ÷ 51? (a) 920 (b) 92 (c) 9200
  7. 7.Best estimate of 929 ÷ 27? (a) 310 (b) 3100 (c) 31
  8. 8.Best estimate of 2560 ÷ 41? (a) 640 (b) 64 (c) 6400
  9. 9.Best estimate of 2967 ÷ 52? (a) 590 (b) 5900 (c) 59
  10. 10.Best estimate of 3525 ÷ 44? (a) 880 (b) 8800 (c) 88
  11. 11.Best estimate of 2663 ÷ 36? (a) 67 (b) 6700 (c) 670
  12. 12.Best estimate of 3908 ÷ 43? (a) 9800 (b) 980 (c) 98
  13. 13.√69 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.4 (d) 8.3
  14. 14.√42 to 1 decimal place? (a) 6.7 (b) 6.5 (c) 6.8 (d) 6.6
  15. 15.Best estimate of 3829 ÷ 46? (a) 7700 (b) 77 (c) 770
  16. 16.√27 to 1 decimal place? (a) 5.1 (b) 5.2 (c) 5.4 (d) 5.3
  17. 17.√74 to 1 decimal place? (a) 8.5 (b) 8.7 (c) 8.6 (d) 8.8
  18. 18.√46 to 1 decimal place? (a) 6.9 (b) 7.0 (c) 7.1 (d) 6.8
  19. 19.√59 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.9 (d) 8.0
  20. 20.√24 to 1 decimal place? (a) 4.7 (b) 5.0 (c) 4.9 (d) 4.8
  21. 21.√86 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.5 (d) 9.2
  22. 22.Best estimate of 5652 ÷ 87? (a) 630 (b) 63 (c) 6300
  23. 23.√92 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.8 (d) 9.5
  24. 24.Best estimate of 942 ÷ 23? (a) 47 (b) 470 (c) 4700
  25. 25.Best estimate of 3682 ÷ 41? (a) 9200 (b) 920 (c) 92
  26. 26.√29 to 1 decimal place? (a) 5.5 (b) 5.3 (c) 5.2 (d) 5.4
  27. 27.Best estimate of 2227 ÷ 56? (a) 37 (b) 370 (c) 3700
  28. 28.√77 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 8.6 (d) 8.7
  29. 29.Best estimate of 6316 ÷ 87? (a) 7000 (b) 700 (c) 70
  30. 30.Best estimate of 1618 ÷ 54? (a) 3200 (b) 320 (c) 32
  31. 31.Best estimate of 4012 ÷ 44? (a) 10000 (b) 1000 (c) 100
  32. 32.√83 to 1 decimal place? (a) 9.4 (b) 9.2 (c) 9.1 (d) 9.3
  33. 33.Best estimate of 5408 ÷ 68? (a) 770 (b) 7700 (c) 77
  34. 34.Best estimate of 2973 ÷ 38? (a) 7400 (b) 74 (c) 740
  35. 35.Best estimate of 4700 ÷ 71? (a) 670 (b) 67 (c) 6700
  36. 36.Best estimate of 4039 ÷ 58? (a) 67 (b) 6700 (c) 670
  37. 37.Best estimate of 775 ÷ 36? (a) 1900 (b) 190 (c) 19
  38. 38.Best estimate of 3906 ÷ 62? (a) 650 (b) 6500 (c) 65
  39. 39.Best estimate of 2005 ÷ 46? (a) 40 (b) 400 (c) 4000
  40. 40.Best estimate of 757 ÷ 37? (a) 1900 (b) 19 (c) 190

Answer key

  1. 6.2
  2. 8.5
  3. 7.6
  4. 7.8
  5. 46
  6. 92
  7. 31
  8. 64
  9. 59
  10. 88
  11. 67
  12. 98
  13. 8.3
  14. 6.5
  15. 77
  16. 5.2
  17. 8.6
  18. 6.8
  19. 7.7
  20. 4.9
  21. 9.3
  22. 63
  23. 9.6
  24. 47
  25. 92
  26. 5.4
  27. 37
  28. 8.8
  29. 70
  30. 32
  31. 100
  32. 9.1
  33. 77
  34. 74
  35. 67
  36. 67
  37. 19
  38. 65
  39. 40
  40. 19

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