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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 699 · 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.√87 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.6 (d) 9.3
  2. 2.Best estimate of 4719 ÷ 66? (a) 67 (b) 670 (c) 6700
  3. 3.√46 to 1 decimal place? (a) 6.8 (b) 7.0 (c) 6.9 (d) 6.7
  4. 4.Best estimate of 4437 ÷ 82? (a) 5500 (b) 550 (c) 55
  5. 5.√61 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.6 (d) 7.5
  6. 6.Best estimate of 1800 ÷ 24? (a) 9000 (b) 900 (c) 90
  7. 7.Best estimate of 2188 ÷ 34? (a) 730 (b) 7300 (c) 73
  8. 8.Best estimate of 5448 ÷ 71? (a) 7800 (b) 78 (c) 780
  9. 9.√28 to 1 decimal place? (a) 5.2 (b) 5.4 (c) 5.3 (d) 5.1
  10. 10.√21 to 1 decimal place? (a) 4.3 (b) 4.6 (c) 4.4 (d) 4.5
  11. 11.Best estimate of 1004 ÷ 26? (a) 3300 (b) 33 (c) 330
  12. 12.√31 to 1 decimal place? (a) 5.5 (b) 5.4 (c) 5.3 (d) 5.6
  13. 13.Best estimate of 2821 ÷ 46? (a) 5600 (b) 560 (c) 56
  14. 14.√80 to 1 decimal place? (a) 9.0 (b) 9.2 (c) 8.9 (d) 9.1
  15. 15.√85 to 1 decimal place? (a) 9.1 (b) 9.3 (c) 9.2 (d) 9.0
  16. 16.Best estimate of 970 ÷ 42? (a) 2400 (b) 240 (c) 24
  17. 17.Best estimate of 1469 ÷ 72? (a) 21 (b) 210 (c) 2100
  18. 18.Best estimate of 3202 ÷ 74? (a) 46 (b) 4600 (c) 460
  19. 19.Best estimate of 1981 ÷ 67? (a) 2800 (b) 280 (c) 28
  20. 20.Best estimate of 4867 ÷ 72? (a) 7000 (b) 700 (c) 70
  21. 21.Best estimate of 4367 ÷ 66? (a) 620 (b) 6200 (c) 62
  22. 22.√69 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.2 (d) 8.1
  23. 23.√43 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.5 (d) 6.8
  24. 24.√94 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 9.7 (d) 10.0
  25. 25.√92 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.9 (d) 9.6
  26. 26.Best estimate of 1756 ÷ 27? (a) 59 (b) 5900 (c) 590
  27. 27.Best estimate of 1652 ÷ 22? (a) 8300 (b) 83 (c) 830
  28. 28.√78 to 1 decimal place? (a) 8.5 (b) 8.8 (c) 8.7 (d) 8.6
  29. 29.Best estimate of 1746 ÷ 32? (a) 580 (b) 5800 (c) 58
  30. 30.Best estimate of 5346 ÷ 81? (a) 670 (b) 67 (c) 6700
  31. 31.√76 to 1 decimal place? (a) 8.7 (b) 8.4 (c) 8.5 (d) 8.6
  32. 32.Best estimate of 1343 ÷ 31? (a) 45 (b) 450 (c) 4500
  33. 33.√40 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.3 (d) 6.4
  34. 34.Best estimate of 466 ÷ 29? (a) 16 (b) 160 (c) 1600
  35. 35.Best estimate of 2086 ÷ 42? (a) 520 (b) 5200 (c) 52
  36. 36.√44 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.9 (d) 6.8
  37. 37.Best estimate of 3985 ÷ 54? (a) 80 (b) 800 (c) 8000
  38. 38.√51 to 1 decimal place? (a) 7.1 (b) 7.0 (c) 6.9 (d) 7.2
  39. 39.√26 to 1 decimal place? (a) 5.2 (b) 5.1 (c) 5.0 (d) 4.9
  40. 40.Best estimate of 1528 ÷ 56? (a) 25 (b) 2500 (c) 250

Answer key

  1. 9.3
  2. 67
  3. 6.8
  4. 55
  5. 7.8
  6. 90
  7. 73
  8. 78
  9. 5.3
  10. 4.6
  11. 33
  12. 5.6
  13. 56
  14. 8.9
  15. 9.2
  16. 24
  17. 21
  18. 46
  19. 28
  20. 70
  21. 62
  22. 8.3
  23. 6.6
  24. 9.7
  25. 9.6
  26. 59
  27. 83
  28. 8.8
  29. 58
  30. 67
  31. 8.7
  32. 45
  33. 6.3
  34. 16
  35. 52
  36. 6.6
  37. 80
  38. 7.1
  39. 5.1
  40. 25

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