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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 426 · 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.√72 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.2 (d) 8.3
  2. 2.Best estimate of 1950 ÷ 32? (a) 650 (b) 6500 (c) 65
  3. 3.Best estimate of 1826 ÷ 24? (a) 910 (b) 9100 (c) 91
  4. 4.Best estimate of 4800 ÷ 53? (a) 960 (b) 96 (c) 9600
  5. 5.Best estimate of 479 ÷ 33? (a) 16 (b) 1600 (c) 160
  6. 6.√74 to 1 decimal place? (a) 8.8 (b) 8.6 (c) 8.7 (d) 8.5
  7. 7.Best estimate of 1211 ÷ 82? (a) 150 (b) 15 (c) 1500
  8. 8.√87 to 1 decimal place? (a) 9.4 (b) 9.2 (c) 9.5 (d) 9.3
  9. 9.Best estimate of 5471 ÷ 72? (a) 780 (b) 78 (c) 7800
  10. 10.√79 to 1 decimal place? (a) 9.0 (b) 8.7 (c) 8.9 (d) 8.8
  11. 11.Best estimate of 1605 ÷ 46? (a) 32 (b) 3200 (c) 320
  12. 12.√82 to 1 decimal place? (a) 9.3 (b) 9.1 (c) 9.2 (d) 9.4
  13. 13.Best estimate of 444 ÷ 24? (a) 220 (b) 22 (c) 2200
  14. 14.Best estimate of 1248 ÷ 31? (a) 420 (b) 4200 (c) 42
  15. 15.√42 to 1 decimal place? (a) 6.5 (b) 6.4 (c) 6.2 (d) 6.3
  16. 16.√46 to 1 decimal place? (a) 6.8 (b) 6.6 (c) 6.7 (d) 6.5
  17. 17.√26 to 1 decimal place? (a) 4.8 (b) 5.1 (c) 4.9 (d) 5.0
  18. 18.Best estimate of 1273 ÷ 31? (a) 420 (b) 4200 (c) 42
  19. 19.Best estimate of 3602 ÷ 42? (a) 900 (b) 90 (c) 9000
  20. 20.Best estimate of 3723 ÷ 71? (a) 53 (b) 530 (c) 5300
  21. 21.√37 to 1 decimal place? (a) 6.2 (b) 6.1 (c) 6.0 (d) 5.9
  22. 22.Best estimate of 3887 ÷ 52? (a) 78 (b) 780 (c) 7800
  23. 23.Best estimate of 1126 ÷ 63? (a) 190 (b) 1900 (c) 19
  24. 24.√89 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.6 (d) 9.7
  25. 25.Best estimate of 6923 ÷ 73? (a) 99 (b) 990 (c) 9900
  26. 26.Best estimate of 6222 ÷ 66? (a) 890 (b) 8900 (c) 89
  27. 27.√48 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 6.9 (d) 6.6
  28. 28.√35 to 1 decimal place? (a) 5.8 (b) 5.7 (c) 5.9 (d) 5.6
  29. 29.√22 to 1 decimal place? (a) 4.7 (b) 4.8 (c) 4.5 (d) 4.6
  30. 30.Best estimate of 480 ÷ 32? (a) 16 (b) 160 (c) 1600
  31. 31.Best estimate of 2143 ÷ 38? (a) 54 (b) 540 (c) 5400
  32. 32.Best estimate of 1017 ÷ 31? (a) 340 (b) 3400 (c) 34
  33. 33.√62 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 7.9 (d) 8.0
  34. 34.Best estimate of 2483 ÷ 26? (a) 830 (b) 83 (c) 8300
  35. 35.Best estimate of 392 ÷ 24? (a) 2000 (b) 20 (c) 200
  36. 36.√69 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.4 (d) 8.3
  37. 37.Best estimate of 2721 ÷ 33? (a) 9100 (b) 910 (c) 91
  38. 38.Best estimate of 2647 ÷ 81? (a) 3300 (b) 33 (c) 330
  39. 39.Best estimate of 2152 ÷ 23? (a) 108 (b) 1080 (c) 10800
  40. 40.Best estimate of 4598 ÷ 61? (a) 7700 (b) 77 (c) 770

Answer key

  1. 8.5
  2. 65
  3. 91
  4. 96
  5. 16
  6. 8.6
  7. 15
  8. 9.3
  9. 78
  10. 8.9
  11. 32
  12. 9.1
  13. 22
  14. 42
  15. 6.5
  16. 6.8
  17. 5.1
  18. 42
  19. 90
  20. 53
  21. 6.1
  22. 78
  23. 19
  24. 9.4
  25. 99
  26. 89
  27. 6.9
  28. 5.9
  29. 4.7
  30. 16
  31. 54
  32. 34
  33. 7.9
  34. 83
  35. 20
  36. 8.3
  37. 91
  38. 33
  39. 108
  40. 77

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