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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 228 · 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 1612 ÷ 79? (a) 2000 (b) 200 (c) 20
  2. 2.Best estimate of 3686 ÷ 69? (a) 5300 (b) 530 (c) 53
  3. 3.√37 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.4 (d) 6.1
  4. 4.Best estimate of 4269 ÷ 73? (a) 61 (b) 610 (c) 6100
  5. 5.√26 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 5.2 (d) 5.1
  6. 6.Best estimate of 1774 ÷ 77? (a) 2200 (b) 22 (c) 220
  7. 7.Best estimate of 2768 ÷ 81? (a) 35 (b) 3500 (c) 350
  8. 8.Best estimate of 1380 ÷ 31? (a) 4600 (b) 46 (c) 460
  9. 9.√82 to 1 decimal place? (a) 9.4 (b) 9.2 (c) 9.3 (d) 9.1
  10. 10.√35 to 1 decimal place? (a) 6.2 (b) 6.0 (c) 6.1 (d) 5.9
  11. 11.Best estimate of 3557 ÷ 87? (a) 400 (b) 4000 (c) 40
  12. 12.√92 to 1 decimal place? (a) 9.8 (b) 9.6 (c) 9.7 (d) 9.9
  13. 13.Best estimate of 1250 ÷ 52? (a) 250 (b) 25 (c) 2500
  14. 14.Best estimate of 2217 ÷ 38? (a) 55 (b) 5500 (c) 550
  15. 15.√96 to 1 decimal place? (a) 9.9 (b) 10.1 (c) 9.8 (d) 10.0
  16. 16.√29 to 1 decimal place? (a) 5.5 (b) 5.2 (c) 5.3 (d) 5.4
  17. 17.√74 to 1 decimal place? (a) 8.3 (b) 8.6 (c) 8.4 (d) 8.5
  18. 18.Best estimate of 2122 ÷ 42? (a) 5300 (b) 530 (c) 53
  19. 19.Best estimate of 957 ÷ 36? (a) 240 (b) 24 (c) 2400
  20. 20.√32 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.8 (d) 5.5
  21. 21.Best estimate of 6090 ÷ 68? (a) 870 (b) 87 (c) 8700
  22. 22.Best estimate of 1267 ÷ 46? (a) 25 (b) 2500 (c) 250
  23. 23.√69 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.5 (d) 8.3
  24. 24.Best estimate of 2502 ÷ 37? (a) 630 (b) 6300 (c) 63
  25. 25.Best estimate of 338 ÷ 24? (a) 1700 (b) 17 (c) 170
  26. 26.Best estimate of 5201 ÷ 73? (a) 740 (b) 7400 (c) 74
  27. 27.√24 to 1 decimal place? (a) 5.0 (b) 5.1 (c) 5.2 (d) 4.9
  28. 28.Best estimate of 3459 ÷ 42? (a) 8600 (b) 860 (c) 86
  29. 29.√76 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.8 (d) 8.9
  30. 30.Best estimate of 2847 ÷ 46? (a) 5700 (b) 57 (c) 570
  31. 31.√47 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 6.9 (d) 6.6
  32. 32.√70 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.1 (d) 8.4
  33. 33.√90 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.4 (d) 9.5
  34. 34.Best estimate of 1222 ÷ 37? (a) 31 (b) 3100 (c) 310
  35. 35.Best estimate of 6757 ÷ 83? (a) 84 (b) 8400 (c) 840
  36. 36.√53 to 1 decimal place? (a) 7.5 (b) 7.4 (c) 7.2 (d) 7.3
  37. 37.Best estimate of 2193 ÷ 44? (a) 5500 (b) 550 (c) 55
  38. 38.Best estimate of 884 ÷ 51? (a) 18 (b) 180 (c) 1800
  39. 39.Best estimate of 1412 ÷ 88? (a) 160 (b) 1600 (c) 16
  40. 40.Best estimate of 4506 ÷ 62? (a) 750 (b) 7500 (c) 75

Answer key

  1. 20
  2. 53
  3. 6.1
  4. 61
  5. 5.1
  6. 22
  7. 35
  8. 46
  9. 9.1
  10. 5.9
  11. 40
  12. 9.6
  13. 25
  14. 55
  15. 9.8
  16. 5.4
  17. 8.6
  18. 53
  19. 24
  20. 5.7
  21. 87
  22. 25
  23. 8.3
  24. 63
  25. 17
  26. 74
  27. 4.9
  28. 86
  29. 8.7
  30. 57
  31. 6.9
  32. 8.4
  33. 9.5
  34. 31
  35. 84
  36. 7.3
  37. 55
  38. 18
  39. 16
  40. 75

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