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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 930 · 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.√21 to 1 decimal place? (a) 4.4 (b) 4.5 (c) 4.6 (d) 4.7
  2. 2.Best estimate of 1604 ÷ 52? (a) 32 (b) 320 (c) 3200
  3. 3.√24 to 1 decimal place? (a) 4.9 (b) 5.2 (c) 5.0 (d) 5.1
  4. 4.√44 to 1 decimal place? (a) 6.6 (b) 6.5 (c) 6.7 (d) 6.4
  5. 5.Best estimate of 1514 ÷ 32? (a) 5000 (b) 500 (c) 50
  6. 6.Best estimate of 7133 ÷ 76? (a) 8900 (b) 89 (c) 890
  7. 7.Best estimate of 1673 ÷ 22? (a) 840 (b) 84 (c) 8400
  8. 8.Best estimate of 1569 ÷ 72? (a) 220 (b) 22 (c) 2200
  9. 9.Best estimate of 1576 ÷ 24? (a) 79 (b) 7900 (c) 790
  10. 10.√58 to 1 decimal place? (a) 7.7 (b) 7.5 (c) 7.6 (d) 7.8
  11. 11.Best estimate of 1308 ÷ 43? (a) 330 (b) 33 (c) 3300
  12. 12.√82 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 9.3 (d) 9.2
  13. 13.√32 to 1 decimal place? (a) 5.7 (b) 6.0 (c) 5.8 (d) 5.9
  14. 14.√35 to 1 decimal place? (a) 5.6 (b) 5.9 (c) 5.7 (d) 5.8
  15. 15.√26 to 1 decimal place? (a) 5.4 (b) 5.1 (c) 5.3 (d) 5.2
  16. 16.√38 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.5 (d) 6.4
  17. 17.√72 to 1 decimal place? (a) 8.5 (b) 8.7 (c) 8.4 (d) 8.6
  18. 18.Best estimate of 5660 ÷ 82? (a) 7100 (b) 71 (c) 710
  19. 19.Best estimate of 4507 ÷ 52? (a) 900 (b) 90 (c) 9000
  20. 20.Best estimate of 266 ÷ 22? (a) 13 (b) 130 (c) 1300
  21. 21.Best estimate of 438 ÷ 29? (a) 1500 (b) 15 (c) 150
  22. 22.Best estimate of 1863 ÷ 31? (a) 62 (b) 6200 (c) 620
  23. 23.√55 to 1 decimal place? (a) 7.5 (b) 7.4 (c) 7.2 (d) 7.3
  24. 24.Best estimate of 4128 ÷ 58? (a) 69 (b) 690 (c) 6900
  25. 25.Best estimate of 4815 ÷ 76? (a) 600 (b) 60 (c) 6000
  26. 26.Best estimate of 1938 ÷ 38? (a) 480 (b) 4800 (c) 48
  27. 27.√76 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.9 (d) 8.6
  28. 28.√67 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.2 (d) 8.1
  29. 29.Best estimate of 2382 ÷ 78? (a) 300 (b) 3000 (c) 30
  30. 30.Best estimate of 2958 ÷ 34? (a) 990 (b) 9900 (c) 99
  31. 31.√51 to 1 decimal place? (a) 6.9 (b) 7.0 (c) 7.1 (d) 6.8
  32. 32.Best estimate of 3438 ÷ 67? (a) 4900 (b) 49 (c) 490
  33. 33.√48 to 1 decimal place? (a) 6.9 (b) 6.6 (c) 6.7 (d) 6.8
  34. 34.Best estimate of 3048 ÷ 74? (a) 44 (b) 4400 (c) 440
  35. 35.Best estimate of 913 ÷ 22? (a) 460 (b) 46 (c) 4600
  36. 36.Best estimate of 7648 ÷ 84? (a) 960 (b) 9600 (c) 96
  37. 37.√90 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.8 (d) 9.7
  38. 38.√70 to 1 decimal place? (a) 8.3 (b) 8.6 (c) 8.4 (d) 8.5
  39. 39.√56 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.6 (d) 7.5
  40. 40.Best estimate of 5357 ÷ 82? (a) 6700 (b) 670 (c) 67

Answer key

  1. 4.6
  2. 32
  3. 4.9
  4. 6.6
  5. 50
  6. 89
  7. 84
  8. 22
  9. 79
  10. 7.6
  11. 33
  12. 9.1
  13. 5.7
  14. 5.9
  15. 5.1
  16. 6.2
  17. 8.5
  18. 71
  19. 90
  20. 13
  21. 15
  22. 62
  23. 7.4
  24. 69
  25. 60
  26. 48
  27. 8.7
  28. 8.2
  29. 30
  30. 99
  31. 7.1
  32. 49
  33. 6.9
  34. 44
  35. 46
  36. 96
  37. 9.5
  38. 8.4
  39. 7.5
  40. 67

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