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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 33 · 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.√48 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 7.1 (d) 7.0
  2. 2.Best estimate of 1159 ÷ 84? (a) 140 (b) 1400 (c) 14
  3. 3.√22 to 1 decimal place? (a) 4.5 (b) 4.6 (c) 4.4 (d) 4.7
  4. 4.√59 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 8.0 (d) 7.7
  5. 5.Best estimate of 1027 ÷ 72? (a) 150 (b) 15 (c) 1500
  6. 6.√31 to 1 decimal place? (a) 5.7 (b) 5.5 (c) 5.6 (d) 5.4
  7. 7.√94 to 1 decimal place? (a) 9.5 (b) 9.8 (c) 9.7 (d) 9.6
  8. 8.Best estimate of 897 ÷ 24? (a) 450 (b) 45 (c) 4500
  9. 9.Best estimate of 1690 ÷ 31? (a) 560 (b) 56 (c) 5600
  10. 10.√50 to 1 decimal place? (a) 7.0 (b) 7.1 (c) 6.9 (d) 7.2
  11. 11.Best estimate of 325 ÷ 26? (a) 1100 (b) 110 (c) 11
  12. 12.√92 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.6 (d) 9.4
  13. 13.√26 to 1 decimal place? (a) 5.1 (b) 4.9 (c) 5.2 (d) 5.0
  14. 14.√21 to 1 decimal place? (a) 4.6 (b) 4.9 (c) 4.8 (d) 4.7
  15. 15.Best estimate of 6984 ÷ 79? (a) 8700 (b) 870 (c) 87
  16. 16.√37 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 6.2 (d) 6.1
  17. 17.√41 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 6.4 (d) 6.3
  18. 18.√42 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.5 (d) 6.2
  19. 19.√89 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.3 (d) 9.4
  20. 20.√55 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.3 (d) 7.5
  21. 21.√76 to 1 decimal place? (a) 8.7 (b) 9.0 (c) 8.9 (d) 8.8
  22. 22.√30 to 1 decimal place? (a) 5.6 (b) 5.4 (c) 5.5 (d) 5.3
  23. 23.Best estimate of 7337 ÷ 82? (a) 9200 (b) 92 (c) 920
  24. 24.Best estimate of 1068 ÷ 23? (a) 5300 (b) 53 (c) 530
  25. 25.Best estimate of 2638 ÷ 36? (a) 6600 (b) 660 (c) 66
  26. 26.√87 to 1 decimal place? (a) 9.6 (b) 9.4 (c) 9.3 (d) 9.5
  27. 27.√24 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 4.7 (d) 4.8
  28. 28.Best estimate of 2953 ÷ 38? (a) 74 (b) 7400 (c) 740
  29. 29.Best estimate of 1331 ÷ 34? (a) 440 (b) 44 (c) 4400
  30. 30.Best estimate of 1620 ÷ 32? (a) 540 (b) 54 (c) 5400
  31. 31.Best estimate of 899 ÷ 37? (a) 2200 (b) 220 (c) 22
  32. 32.√90 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.5 (d) 9.6
  33. 33.Best estimate of 3217 ÷ 89? (a) 36 (b) 3600 (c) 360
  34. 34.Best estimate of 487 ÷ 22? (a) 240 (b) 2400 (c) 24
  35. 35.Best estimate of 1676 ÷ 61? (a) 28 (b) 280 (c) 2800
  36. 36.√29 to 1 decimal place? (a) 5.4 (b) 5.2 (c) 5.5 (d) 5.3
  37. 37.√66 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 8.0 (d) 7.9
  38. 38.√28 to 1 decimal place? (a) 5.0 (b) 5.2 (c) 5.3 (d) 5.1
  39. 39.Best estimate of 1254 ÷ 36? (a) 310 (b) 3100 (c) 31
  40. 40.√43 to 1 decimal place? (a) 6.6 (b) 6.8 (c) 6.9 (d) 6.7

Answer key

  1. 6.9
  2. 14
  3. 4.7
  4. 7.7
  5. 15
  6. 5.6
  7. 9.7
  8. 45
  9. 56
  10. 7.1
  11. 11
  12. 9.6
  13. 5.1
  14. 4.6
  15. 87
  16. 6.1
  17. 6.4
  18. 6.5
  19. 9.4
  20. 7.4
  21. 8.7
  22. 5.5
  23. 92
  24. 53
  25. 66
  26. 9.3
  27. 4.9
  28. 74
  29. 44
  30. 54
  31. 22
  32. 9.5
  33. 36
  34. 24
  35. 28
  36. 5.4
  37. 8.1
  38. 5.3
  39. 31
  40. 6.6

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