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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 842 · 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 1607 ÷ 28? (a) 5400 (b) 540 (c) 54
  2. 2.Best estimate of 1544 ÷ 38? (a) 39 (b) 3900 (c) 390
  3. 3.√80 to 1 decimal place? (a) 8.7 (b) 8.9 (c) 8.8 (d) 8.6
  4. 4.√98 to 1 decimal place? (a) 9.6 (b) 9.9 (c) 9.8 (d) 9.7
  5. 5.Best estimate of 3572 ÷ 43? (a) 8900 (b) 89 (c) 890
  6. 6.√41 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.5 (d) 6.2
  7. 7.Best estimate of 1076 ÷ 32? (a) 360 (b) 36 (c) 3600
  8. 8.Best estimate of 3547 ÷ 58? (a) 5900 (b) 590 (c) 59
  9. 9.√65 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.1 (d) 8.0
  10. 10.√89 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.2 (d) 9.5
  11. 11.Best estimate of 1218 ÷ 42? (a) 30 (b) 300 (c) 3000
  12. 12.√79 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.9 (d) 8.6
  13. 13.Best estimate of 2799 ÷ 32? (a) 930 (b) 93 (c) 9300
  14. 14.√24 to 1 decimal place? (a) 5.1 (b) 5.2 (c) 5.0 (d) 4.9
  15. 15.Best estimate of 736 ÷ 56? (a) 12 (b) 1200 (c) 120
  16. 16.Best estimate of 1392 ÷ 67? (a) 200 (b) 20 (c) 2000
  17. 17.√51 to 1 decimal place? (a) 7.1 (b) 6.9 (c) 7.0 (d) 6.8
  18. 18.√66 to 1 decimal place? (a) 8.2 (b) 8.4 (c) 8.3 (d) 8.1
  19. 19.√40 to 1 decimal place? (a) 6.5 (b) 6.4 (c) 6.3 (d) 6.2
  20. 20.Best estimate of 990 ÷ 24? (a) 5000 (b) 500 (c) 50
  21. 21.√28 to 1 decimal place? (a) 5.1 (b) 5.3 (c) 5.0 (d) 5.2
  22. 22.Best estimate of 1534 ÷ 53? (a) 3100 (b) 310 (c) 31
  23. 23.Best estimate of 7282 ÷ 76? (a) 910 (b) 91 (c) 9100
  24. 24.Best estimate of 4172 ÷ 87? (a) 460 (b) 46 (c) 4600
  25. 25.Best estimate of 2550 ÷ 72? (a) 360 (b) 36 (c) 3600
  26. 26.√31 to 1 decimal place? (a) 5.8 (b) 5.7 (c) 5.6 (d) 5.9
  27. 27.Best estimate of 787 ÷ 33? (a) 260 (b) 2600 (c) 26
  28. 28.Best estimate of 1393 ÷ 54? (a) 28 (b) 2800 (c) 280
  29. 29.Best estimate of 864 ÷ 28? (a) 2900 (b) 290 (c) 29
  30. 30.Best estimate of 2459 ÷ 34? (a) 82 (b) 8200 (c) 820
  31. 31.√23 to 1 decimal place? (a) 4.6 (b) 4.8 (c) 4.9 (d) 4.7
  32. 32.Best estimate of 2283 ÷ 77? (a) 2900 (b) 29 (c) 290
  33. 33.Best estimate of 4923 ÷ 63? (a) 820 (b) 8200 (c) 82
  34. 34.√32 to 1 decimal place? (a) 5.8 (b) 5.5 (c) 5.7 (d) 5.6
  35. 35.√96 to 1 decimal place? (a) 10.0 (b) 9.7 (c) 9.9 (d) 9.8
  36. 36.Best estimate of 474 ÷ 39? (a) 1200 (b) 12 (c) 120
  37. 37.Best estimate of 881 ÷ 32? (a) 29 (b) 290 (c) 2900
  38. 38.Best estimate of 747 ÷ 32? (a) 250 (b) 25 (c) 2500
  39. 39.√62 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 7.9 (d) 7.8
  40. 40.√50 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 7.1 (d) 7.0

Answer key

  1. 54
  2. 39
  3. 8.9
  4. 9.9
  5. 89
  6. 6.4
  7. 36
  8. 59
  9. 8.1
  10. 9.4
  11. 30
  12. 8.9
  13. 93
  14. 4.9
  15. 12
  16. 20
  17. 7.1
  18. 8.1
  19. 6.3
  20. 50
  21. 5.3
  22. 31
  23. 91
  24. 46
  25. 36
  26. 5.6
  27. 26
  28. 28
  29. 29
  30. 82
  31. 4.8
  32. 29
  33. 82
  34. 5.7
  35. 9.8
  36. 12
  37. 29
  38. 25
  39. 7.9
  40. 7.1

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