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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 351 · 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 1155 ÷ 26? (a) 390 (b) 3900 (c) 39
  2. 2.√53 to 1 decimal place? (a) 7.3 (b) 7.2 (c) 7.1 (d) 7.0
  3. 3.√38 to 1 decimal place? (a) 6.0 (b) 6.3 (c) 6.1 (d) 6.2
  4. 4.Best estimate of 3664 ÷ 76? (a) 46 (b) 460 (c) 4600
  5. 5.Best estimate of 4424 ÷ 63? (a) 74 (b) 7400 (c) 740
  6. 6.Best estimate of 2588 ÷ 62? (a) 43 (b) 4300 (c) 430
  7. 7.√82 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 8.9 (d) 8.8
  8. 8.Best estimate of 1621 ÷ 29? (a) 540 (b) 5400 (c) 54
  9. 9.Best estimate of 1016 ÷ 52? (a) 2000 (b) 20 (c) 200
  10. 10.Best estimate of 4409 ÷ 68? (a) 630 (b) 6300 (c) 63
  11. 11.Best estimate of 1239 ÷ 87? (a) 1400 (b) 140 (c) 14
  12. 12.Best estimate of 3265 ÷ 74? (a) 470 (b) 47 (c) 4700
  13. 13.√30 to 1 decimal place? (a) 5.8 (b) 5.7 (c) 5.5 (d) 5.6
  14. 14.√50 to 1 decimal place? (a) 7.2 (b) 7.0 (c) 7.1 (d) 6.9
  15. 15.Best estimate of 6383 ÷ 87? (a) 7100 (b) 71 (c) 710
  16. 16.Best estimate of 1010 ÷ 39? (a) 2500 (b) 25 (c) 250
  17. 17.Best estimate of 2331 ÷ 86? (a) 2600 (b) 26 (c) 260
  18. 18.Best estimate of 4799 ÷ 82? (a) 600 (b) 60 (c) 6000
  19. 19.Best estimate of 1064 ÷ 66? (a) 150 (b) 1500 (c) 15
  20. 20.Best estimate of 681 ÷ 51? (a) 140 (b) 14 (c) 1400
  21. 21.Best estimate of 2523 ÷ 49? (a) 500 (b) 5000 (c) 50
  22. 22.Best estimate of 1023 ÷ 23? (a) 51 (b) 5100 (c) 510
  23. 23.√67 to 1 decimal place? (a) 8.2 (b) 8.0 (c) 8.1 (d) 8.3
  24. 24.Best estimate of 5580 ÷ 83? (a) 70 (b) 700 (c) 7000
  25. 25.Best estimate of 4783 ÷ 51? (a) 9600 (b) 96 (c) 960
  26. 26.√32 to 1 decimal place? (a) 5.7 (b) 5.4 (c) 5.5 (d) 5.6
  27. 27.√41 to 1 decimal place? (a) 6.3 (b) 6.1 (c) 6.4 (d) 6.2
  28. 28.Best estimate of 1300 ÷ 36? (a) 3300 (b) 330 (c) 33
  29. 29.√24 to 1 decimal place? (a) 5.0 (b) 5.1 (c) 4.9 (d) 5.2
  30. 30.Best estimate of 2531 ÷ 87? (a) 280 (b) 28 (c) 2800
  31. 31.√94 to 1 decimal place? (a) 9.8 (b) 9.6 (c) 9.7 (d) 9.5
  32. 32.√74 to 1 decimal place? (a) 8.8 (b) 8.6 (c) 8.7 (d) 8.5
  33. 33.Best estimate of 970 ÷ 68? (a) 1400 (b) 140 (c) 14
  34. 34.√51 to 1 decimal place? (a) 7.0 (b) 7.1 (c) 7.2 (d) 7.3
  35. 35.Best estimate of 2469 ÷ 26? (a) 8200 (b) 820 (c) 82
  36. 36.Best estimate of 1475 ÷ 28? (a) 490 (b) 4900 (c) 49
  37. 37.√65 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 7.8 (d) 7.9
  38. 38.Best estimate of 2744 ÷ 51? (a) 55 (b) 5500 (c) 550
  39. 39.Best estimate of 3315 ÷ 66? (a) 47 (b) 470 (c) 4700
  40. 40.Best estimate of 1422 ÷ 24? (a) 710 (b) 7100 (c) 71

Answer key

  1. 39
  2. 7.3
  3. 6.2
  4. 46
  5. 74
  6. 43
  7. 9.1
  8. 54
  9. 20
  10. 63
  11. 14
  12. 47
  13. 5.5
  14. 7.1
  15. 71
  16. 25
  17. 26
  18. 60
  19. 15
  20. 14
  21. 50
  22. 51
  23. 8.2
  24. 70
  25. 96
  26. 5.7
  27. 6.4
  28. 33
  29. 4.9
  30. 28
  31. 9.7
  32. 8.6
  33. 14
  34. 7.1
  35. 82
  36. 49
  37. 8.1
  38. 55
  39. 47
  40. 71

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