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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 499 · 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 1105 ÷ 21? (a) 550 (b) 55 (c) 5500
  2. 2.Best estimate of 2040 ÷ 48? (a) 410 (b) 4100 (c) 41
  3. 3.√26 to 1 decimal place? (a) 5.1 (b) 5.2 (c) 5.4 (d) 5.3
  4. 4.√94 to 1 decimal place? (a) 9.6 (b) 9.9 (c) 9.8 (d) 9.7
  5. 5.√89 to 1 decimal place? (a) 9.2 (b) 9.4 (c) 9.3 (d) 9.5
  6. 6.Best estimate of 2845 ÷ 76? (a) 36 (b) 3600 (c) 360
  7. 7.Best estimate of 2889 ÷ 53? (a) 58 (b) 5800 (c) 580
  8. 8.√79 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 8.6 (d) 8.7
  9. 9.Best estimate of 928 ÷ 52? (a) 1900 (b) 190 (c) 19
  10. 10.√84 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.0 (d) 8.9
  11. 11.Best estimate of 4587 ÷ 62? (a) 76 (b) 760 (c) 7600
  12. 12.Best estimate of 2165 ÷ 26? (a) 72 (b) 720 (c) 7200
  13. 13.Best estimate of 1265 ÷ 23? (a) 6300 (b) 630 (c) 63
  14. 14.√58 to 1 decimal place? (a) 7.3 (b) 7.5 (c) 7.4 (d) 7.6
  15. 15.Best estimate of 2433 ÷ 87? (a) 27 (b) 2700 (c) 270
  16. 16.Best estimate of 420 ÷ 23? (a) 21 (b) 2100 (c) 210
  17. 17.√40 to 1 decimal place? (a) 6.3 (b) 6.6 (c) 6.4 (d) 6.5
  18. 18.Best estimate of 1472 ÷ 27? (a) 49 (b) 4900 (c) 490
  19. 19.√61 to 1 decimal place? (a) 7.8 (b) 8.1 (c) 7.9 (d) 8.0
  20. 20.√34 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.8 (d) 5.7
  21. 21.√74 to 1 decimal place? (a) 8.4 (b) 8.6 (c) 8.5 (d) 8.7
  22. 22.Best estimate of 3070 ÷ 61? (a) 51 (b) 510 (c) 5100
  23. 23.√85 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.0 (d) 8.9
  24. 24.Best estimate of 1467 ÷ 38? (a) 37 (b) 3700 (c) 370
  25. 25.Best estimate of 748 ÷ 42? (a) 1900 (b) 190 (c) 19
  26. 26.Best estimate of 6090 ÷ 66? (a) 87 (b) 8700 (c) 870
  27. 27.Best estimate of 1099 ÷ 26? (a) 37 (b) 3700 (c) 370
  28. 28.Best estimate of 4077 ÷ 72? (a) 5800 (b) 58 (c) 580
  29. 29.√51 to 1 decimal place? (a) 7.2 (b) 6.9 (c) 7.1 (d) 7.0
  30. 30.√27 to 1 decimal place? (a) 4.9 (b) 5.0 (c) 5.1 (d) 5.2
  31. 31.√24 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 4.7 (d) 4.8
  32. 32.Best estimate of 2314 ÷ 36? (a) 5800 (b) 580 (c) 58
  33. 33.Best estimate of 2843 ÷ 52? (a) 5700 (b) 57 (c) 570
  34. 34.√22 to 1 decimal place? (a) 4.7 (b) 4.8 (c) 5.0 (d) 4.9
  35. 35.Best estimate of 2485 ÷ 54? (a) 5000 (b) 500 (c) 50
  36. 36.Best estimate of 1206 ÷ 84? (a) 1500 (b) 15 (c) 150
  37. 37.Best estimate of 1452 ÷ 84? (a) 1800 (b) 18 (c) 180
  38. 38.Best estimate of 2121 ÷ 73? (a) 300 (b) 30 (c) 3000
  39. 39.Best estimate of 2999 ÷ 36? (a) 7500 (b) 750 (c) 75
  40. 40.Best estimate of 2016 ÷ 26? (a) 670 (b) 6700 (c) 67

Answer key

  1. 55
  2. 41
  3. 5.1
  4. 9.7
  5. 9.4
  6. 36
  7. 58
  8. 8.9
  9. 19
  10. 9.2
  11. 76
  12. 72
  13. 63
  14. 7.6
  15. 27
  16. 21
  17. 6.3
  18. 49
  19. 7.8
  20. 5.8
  21. 8.6
  22. 51
  23. 9.2
  24. 37
  25. 19
  26. 87
  27. 37
  28. 58
  29. 7.1
  30. 5.2
  31. 4.9
  32. 58
  33. 57
  34. 4.7
  35. 50
  36. 15
  37. 18
  38. 30
  39. 75
  40. 67

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