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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 296 · 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 395 ÷ 24? (a) 2000 (b) 20 (c) 200
  2. 2.Best estimate of 432 ÷ 31? (a) 14 (b) 140 (c) 1400
  3. 3.√29 to 1 decimal place? (a) 5.4 (b) 5.5 (c) 5.6 (d) 5.3
  4. 4.√74 to 1 decimal place? (a) 8.4 (b) 8.7 (c) 8.5 (d) 8.6
  5. 5.Best estimate of 1574 ÷ 21? (a) 790 (b) 79 (c) 7900
  6. 6.√55 to 1 decimal place? (a) 7.4 (b) 7.1 (c) 7.3 (d) 7.2
  7. 7.Best estimate of 6692 ÷ 73? (a) 96 (b) 960 (c) 9600
  8. 8.√92 to 1 decimal place? (a) 9.7 (b) 9.4 (c) 9.5 (d) 9.6
  9. 9.Best estimate of 3357 ÷ 39? (a) 840 (b) 84 (c) 8400
  10. 10.Best estimate of 1037 ÷ 36? (a) 2600 (b) 26 (c) 260
  11. 11.Best estimate of 894 ÷ 23? (a) 450 (b) 4500 (c) 45
  12. 12.Best estimate of 3525 ÷ 44? (a) 88 (b) 880 (c) 8800
  13. 13.Best estimate of 2344 ÷ 47? (a) 47 (b) 4700 (c) 470
  14. 14.Best estimate of 1012 ÷ 37? (a) 250 (b) 25 (c) 2500
  15. 15.√62 to 1 decimal place? (a) 7.8 (b) 8.1 (c) 7.9 (d) 8.0
  16. 16.√88 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.6 (d) 9.3
  17. 17.Best estimate of 331 ÷ 24? (a) 17 (b) 170 (c) 1700
  18. 18.Best estimate of 1817 ÷ 59? (a) 3000 (b) 30 (c) 300
  19. 19.Best estimate of 4385 ÷ 59? (a) 73 (b) 7300 (c) 730
  20. 20.√21 to 1 decimal place? (a) 4.9 (b) 4.6 (c) 4.7 (d) 4.8
  21. 21.Best estimate of 2283 ÷ 71? (a) 3300 (b) 330 (c) 33
  22. 22.√32 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 5.7 (d) 5.8
  23. 23.√38 to 1 decimal place? (a) 6.3 (b) 6.0 (c) 6.2 (d) 6.1
  24. 24.Best estimate of 1770 ÷ 86? (a) 20 (b) 200 (c) 2000
  25. 25.Best estimate of 4334 ÷ 82? (a) 54 (b) 5400 (c) 540
  26. 26.Best estimate of 2831 ÷ 51? (a) 57 (b) 570 (c) 5700
  27. 27.√42 to 1 decimal place? (a) 6.6 (b) 6.5 (c) 6.7 (d) 6.4
  28. 28.√79 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 8.9 (d) 8.8
  29. 29.√76 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.4 (d) 8.5
  30. 30.√41 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.4 (d) 6.1
  31. 31.√87 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.3 (d) 9.0
  32. 32.Best estimate of 1585 ÷ 77? (a) 20 (b) 2000 (c) 200
  33. 33.√86 to 1 decimal place? (a) 9.1 (b) 9.4 (c) 9.2 (d) 9.3
  34. 34.√44 to 1 decimal place? (a) 6.3 (b) 6.6 (c) 6.5 (d) 6.4
  35. 35.Best estimate of 879 ÷ 72? (a) 13 (b) 130 (c) 1300
  36. 36.Best estimate of 2090 ÷ 61? (a) 3500 (b) 350 (c) 35
  37. 37.Best estimate of 2755 ÷ 59? (a) 46 (b) 460 (c) 4600
  38. 38.Best estimate of 2725 ÷ 63? (a) 45 (b) 450 (c) 4500
  39. 39.Best estimate of 3844 ÷ 66? (a) 5500 (b) 550 (c) 55
  40. 40.Best estimate of 1412 ÷ 66? (a) 2000 (b) 200 (c) 20

Answer key

  1. 20
  2. 14
  3. 5.4
  4. 8.6
  5. 79
  6. 7.4
  7. 96
  8. 9.6
  9. 84
  10. 26
  11. 45
  12. 88
  13. 47
  14. 25
  15. 7.9
  16. 9.4
  17. 17
  18. 30
  19. 73
  20. 4.6
  21. 33
  22. 5.7
  23. 6.2
  24. 20
  25. 54
  26. 57
  27. 6.5
  28. 8.9
  29. 8.7
  30. 6.4
  31. 9.3
  32. 20
  33. 9.3
  34. 6.6
  35. 13
  36. 35
  37. 46
  38. 45
  39. 55
  40. 20

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