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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 804 · 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) 4.6 (b) 4.7 (c) 4.9 (d) 4.8
  2. 2.Best estimate of 699 ÷ 22? (a) 35 (b) 350 (c) 3500
  3. 3.√45 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.4 (d) 6.5
  4. 4.√37 to 1 decimal place? (a) 6.0 (b) 6.1 (c) 6.2 (d) 5.9
  5. 5.√96 to 1 decimal place? (a) 9.7 (b) 9.9 (c) 9.6 (d) 9.8
  6. 6.Best estimate of 1258 ÷ 56? (a) 210 (b) 2100 (c) 21
  7. 7.√20 to 1 decimal place? (a) 4.4 (b) 4.3 (c) 4.2 (d) 4.5
  8. 8.Best estimate of 942 ÷ 34? (a) 3100 (b) 31 (c) 310
  9. 9.√67 to 1 decimal place? (a) 7.9 (b) 8.1 (c) 8.0 (d) 8.2
  10. 10.Best estimate of 2102 ÷ 58? (a) 35 (b) 350 (c) 3500
  11. 11.√61 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.1 (d) 7.8
  12. 12.Best estimate of 2276 ÷ 29? (a) 7600 (b) 76 (c) 760
  13. 13.Best estimate of 1066 ÷ 41? (a) 270 (b) 2700 (c) 27
  14. 14.Best estimate of 2506 ÷ 28? (a) 840 (b) 84 (c) 8400
  15. 15.Best estimate of 2794 ÷ 46? (a) 5600 (b) 560 (c) 56
  16. 16.√92 to 1 decimal place? (a) 9.9 (b) 9.6 (c) 9.8 (d) 9.7
  17. 17.Best estimate of 857 ÷ 27? (a) 290 (b) 2900 (c) 29
  18. 18.√46 to 1 decimal place? (a) 6.7 (b) 7.0 (c) 6.9 (d) 6.8
  19. 19.Best estimate of 4208 ÷ 52? (a) 840 (b) 8400 (c) 84
  20. 20.Best estimate of 1285 ÷ 21? (a) 640 (b) 64 (c) 6400
  21. 21.Best estimate of 805 ÷ 22? (a) 400 (b) 4000 (c) 40
  22. 22.Best estimate of 1292 ÷ 69? (a) 1800 (b) 18 (c) 180
  23. 23.√35 to 1 decimal place? (a) 6.0 (b) 5.7 (c) 5.9 (d) 5.8
  24. 24.Best estimate of 1241 ÷ 41? (a) 31 (b) 3100 (c) 310
  25. 25.Best estimate of 1347 ÷ 28? (a) 4500 (b) 450 (c) 45
  26. 26.Best estimate of 2219 ÷ 77? (a) 280 (b) 2800 (c) 28
  27. 27.Best estimate of 2205 ÷ 34? (a) 74 (b) 740 (c) 7400
  28. 28.√69 to 1 decimal place? (a) 8.5 (b) 8.4 (c) 8.3 (d) 8.2
  29. 29.√31 to 1 decimal place? (a) 5.8 (b) 5.6 (c) 5.9 (d) 5.7
  30. 30.Best estimate of 2461 ÷ 68? (a) 35 (b) 350 (c) 3500
  31. 31.Best estimate of 973 ÷ 81? (a) 120 (b) 1200 (c) 12
  32. 32.Best estimate of 8014 ÷ 86? (a) 89 (b) 8900 (c) 890
  33. 33.√40 to 1 decimal place? (a) 6.6 (b) 6.3 (c) 6.4 (d) 6.5
  34. 34.Best estimate of 2037 ÷ 41? (a) 5100 (b) 51 (c) 510
  35. 35.Best estimate of 3504 ÷ 89? (a) 3900 (b) 390 (c) 39
  36. 36.Best estimate of 4105 ÷ 56? (a) 680 (b) 68 (c) 6800
  37. 37.Best estimate of 660 ÷ 47? (a) 130 (b) 13 (c) 1300
  38. 38.√84 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.0 (d) 8.9
  39. 39.Best estimate of 924 ÷ 21? (a) 46 (b) 4600 (c) 460
  40. 40.√86 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.6 (d) 9.3

Answer key

  1. 4.8
  2. 35
  3. 6.7
  4. 6.1
  5. 9.8
  6. 21
  7. 4.5
  8. 31
  9. 8.2
  10. 35
  11. 7.8
  12. 76
  13. 27
  14. 84
  15. 56
  16. 9.6
  17. 29
  18. 6.8
  19. 84
  20. 64
  21. 40
  22. 18
  23. 5.9
  24. 31
  25. 45
  26. 28
  27. 74
  28. 8.3
  29. 5.6
  30. 35
  31. 12
  32. 89
  33. 6.3
  34. 51
  35. 39
  36. 68
  37. 13
  38. 9.2
  39. 46
  40. 9.3

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