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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 483 · 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.√88 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.3 (d) 9.5
  2. 2.Best estimate of 2134 ÷ 61? (a) 36 (b) 3600 (c) 360
  3. 3.Best estimate of 5910 ÷ 62? (a) 990 (b) 9900 (c) 99
  4. 4.√27 to 1 decimal place? (a) 5.3 (b) 5.2 (c) 5.1 (d) 5.4
  5. 5.√55 to 1 decimal place? (a) 7.7 (b) 7.4 (c) 7.5 (d) 7.6
  6. 6.√80 to 1 decimal place? (a) 9.2 (b) 9.0 (c) 9.1 (d) 8.9
  7. 7.√53 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.1 (d) 7.2
  8. 8.Best estimate of 2359 ÷ 52? (a) 470 (b) 4700 (c) 47
  9. 9.√87 to 1 decimal place? (a) 9.2 (b) 9.4 (c) 9.3 (d) 9.5
  10. 10.Best estimate of 3552 ÷ 51? (a) 7100 (b) 710 (c) 71
  11. 11.√94 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 10.0 (d) 9.9
  12. 12.Best estimate of 3972 ÷ 57? (a) 660 (b) 6600 (c) 66
  13. 13.√96 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.5 (d) 9.8
  14. 14.√21 to 1 decimal place? (a) 4.3 (b) 4.6 (c) 4.4 (d) 4.5
  15. 15.Best estimate of 6722 ÷ 78? (a) 8400 (b) 84 (c) 840
  16. 16.Best estimate of 1519 ÷ 31? (a) 510 (b) 5100 (c) 51
  17. 17.Best estimate of 839 ÷ 39? (a) 21 (b) 2100 (c) 210
  18. 18.Best estimate of 522 ÷ 32? (a) 170 (b) 1700 (c) 17
  19. 19.√43 to 1 decimal place? (a) 6.8 (b) 6.6 (c) 6.9 (d) 6.7
  20. 20.Best estimate of 1909 ÷ 38? (a) 48 (b) 4800 (c) 480
  21. 21.√90 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.3 (d) 9.4
  22. 22.Best estimate of 3092 ÷ 82? (a) 39 (b) 3900 (c) 390
  23. 23.Best estimate of 1223 ÷ 76? (a) 1500 (b) 15 (c) 150
  24. 24.Best estimate of 3823 ÷ 52? (a) 760 (b) 7600 (c) 76
  25. 25.√82 to 1 decimal place? (a) 9.1 (b) 8.9 (c) 9.0 (d) 9.2
  26. 26.Best estimate of 2133 ÷ 61? (a) 36 (b) 3600 (c) 360
  27. 27.Best estimate of 2183 ÷ 37? (a) 5500 (b) 550 (c) 55
  28. 28.Best estimate of 1140 ÷ 49? (a) 23 (b) 230 (c) 2300
  29. 29.√30 to 1 decimal place? (a) 5.8 (b) 5.7 (c) 5.6 (d) 5.5
  30. 30.Best estimate of 987 ÷ 21? (a) 49 (b) 4900 (c) 490
  31. 31.√51 to 1 decimal place? (a) 6.9 (b) 7.0 (c) 7.1 (d) 6.8
  32. 32.√46 to 1 decimal place? (a) 6.8 (b) 6.5 (c) 6.7 (d) 6.6
  33. 33.Best estimate of 1288 ÷ 36? (a) 32 (b) 320 (c) 3200
  34. 34.Best estimate of 3930 ÷ 46? (a) 7900 (b) 790 (c) 79
  35. 35.Best estimate of 4020 ÷ 76? (a) 50 (b) 500 (c) 5000
  36. 36.√98 to 1 decimal place? (a) 10.2 (b) 9.9 (c) 10.1 (d) 10.0
  37. 37.Best estimate of 980 ÷ 21? (a) 4900 (b) 490 (c) 49
  38. 38.Best estimate of 1635 ÷ 38? (a) 410 (b) 4100 (c) 41
  39. 39.√28 to 1 decimal place? (a) 5.2 (b) 5.1 (c) 5.3 (d) 5.0
  40. 40.Best estimate of 2525 ÷ 86? (a) 28 (b) 280 (c) 2800

Answer key

  1. 9.4
  2. 36
  3. 99
  4. 5.2
  5. 7.4
  6. 8.9
  7. 7.3
  8. 47
  9. 9.3
  10. 71
  11. 9.7
  12. 66
  13. 9.8
  14. 4.6
  15. 84
  16. 51
  17. 21
  18. 17
  19. 6.6
  20. 48
  21. 9.5
  22. 39
  23. 15
  24. 76
  25. 9.1
  26. 36
  27. 55
  28. 23
  29. 5.5
  30. 49
  31. 7.1
  32. 6.8
  33. 32
  34. 79
  35. 50
  36. 9.9
  37. 49
  38. 41
  39. 5.3
  40. 28

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