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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 170 · 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 2256 ÷ 72? (a) 32 (b) 320 (c) 3200
  2. 2.Best estimate of 7643 ÷ 83? (a) 960 (b) 9600 (c) 96
  3. 3.√29 to 1 decimal place? (a) 5.5 (b) 5.4 (c) 5.7 (d) 5.6
  4. 4.√27 to 1 decimal place? (a) 4.9 (b) 5.1 (c) 5.2 (d) 5.0
  5. 5.Best estimate of 1943 ÷ 79? (a) 24 (b) 2400 (c) 240
  6. 6.Best estimate of 1586 ÷ 74? (a) 23 (b) 230 (c) 2300
  7. 7.Best estimate of 1664 ÷ 53? (a) 3300 (b) 330 (c) 33
  8. 8.Best estimate of 7621 ÷ 84? (a) 9500 (b) 95 (c) 950
  9. 9.√37 to 1 decimal place? (a) 6.3 (b) 6.1 (c) 6.2 (d) 6.4
  10. 10.Best estimate of 1095 ÷ 36? (a) 270 (b) 2700 (c) 27
  11. 11.Best estimate of 5621 ÷ 89? (a) 620 (b) 6200 (c) 62
  12. 12.Best estimate of 1370 ÷ 76? (a) 1700 (b) 170 (c) 17
  13. 13.Best estimate of 5593 ÷ 59? (a) 930 (b) 9300 (c) 93
  14. 14.Best estimate of 2090 ÷ 42? (a) 520 (b) 5200 (c) 52
  15. 15.√75 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.5 (d) 8.6
  16. 16.Best estimate of 1739 ÷ 53? (a) 3500 (b) 35 (c) 350
  17. 17.√20 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 4.5 (d) 4.6
  18. 18.√32 to 1 decimal place? (a) 5.8 (b) 5.9 (c) 5.6 (d) 5.7
  19. 19.Best estimate of 2949 ÷ 36? (a) 74 (b) 7400 (c) 740
  20. 20.Best estimate of 841 ÷ 21? (a) 420 (b) 4200 (c) 42
  21. 21.Best estimate of 1097 ÷ 54? (a) 220 (b) 22 (c) 2200
  22. 22.Best estimate of 1916 ÷ 48? (a) 3800 (b) 380 (c) 38
  23. 23.Best estimate of 2202 ÷ 43? (a) 550 (b) 5500 (c) 55
  24. 24.Best estimate of 3272 ÷ 56? (a) 5500 (b) 55 (c) 550
  25. 25.Best estimate of 1147 ÷ 32? (a) 380 (b) 38 (c) 3800
  26. 26.Best estimate of 2134 ÷ 32? (a) 710 (b) 7100 (c) 71
  27. 27.√65 to 1 decimal place? (a) 8.4 (b) 8.1 (c) 8.3 (d) 8.2
  28. 28.√58 to 1 decimal place? (a) 7.6 (b) 7.8 (c) 7.7 (d) 7.5
  29. 29.Best estimate of 1965 ÷ 82? (a) 2500 (b) 250 (c) 25
  30. 30.Best estimate of 5686 ÷ 68? (a) 81 (b) 810 (c) 8100
  31. 31.√66 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 7.8 (d) 8.1
  32. 32.Best estimate of 1065 ÷ 42? (a) 2700 (b) 27 (c) 270
  33. 33.√42 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.5 (d) 6.4
  34. 34.Best estimate of 5355 ÷ 83? (a) 6700 (b) 670 (c) 67
  35. 35.√41 to 1 decimal place? (a) 6.3 (b) 6.6 (c) 6.4 (d) 6.5
  36. 36.Best estimate of 4817 ÷ 77? (a) 60 (b) 600 (c) 6000
  37. 37.√94 to 1 decimal place? (a) 10.0 (b) 9.7 (c) 9.8 (d) 9.9
  38. 38.√35 to 1 decimal place? (a) 5.9 (b) 6.2 (c) 6.1 (d) 6.0
  39. 39.Best estimate of 3565 ÷ 38? (a) 89 (b) 890 (c) 8900
  40. 40.Best estimate of 4516 ÷ 48? (a) 900 (b) 90 (c) 9000

Answer key

  1. 32
  2. 96
  3. 5.4
  4. 5.2
  5. 24
  6. 23
  7. 33
  8. 95
  9. 6.1
  10. 27
  11. 62
  12. 17
  13. 93
  14. 52
  15. 8.7
  16. 35
  17. 4.5
  18. 5.7
  19. 74
  20. 42
  21. 22
  22. 38
  23. 55
  24. 55
  25. 38
  26. 71
  27. 8.1
  28. 7.6
  29. 25
  30. 81
  31. 8.1
  32. 27
  33. 6.5
  34. 67
  35. 6.4
  36. 60
  37. 9.7
  38. 5.9
  39. 89
  40. 90

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