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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 116 · 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 892 ÷ 27? (a) 300 (b) 30 (c) 3000
  2. 2.Best estimate of 1162 ÷ 29? (a) 390 (b) 39 (c) 3900
  3. 3.√98 to 1 decimal place? (a) 10.1 (b) 9.8 (c) 10.0 (d) 9.9
  4. 4.Best estimate of 4673 ÷ 52? (a) 93 (b) 9300 (c) 930
  5. 5.√26 to 1 decimal place? (a) 5.1 (b) 5.4 (c) 5.3 (d) 5.2
  6. 6.Best estimate of 5295 ÷ 69? (a) 7600 (b) 76 (c) 760
  7. 7.Best estimate of 3379 ÷ 81? (a) 42 (b) 420 (c) 4200
  8. 8.Best estimate of 6287 ÷ 72? (a) 900 (b) 9000 (c) 90
  9. 9.√51 to 1 decimal place? (a) 7.0 (b) 6.8 (c) 6.9 (d) 7.1
  10. 10.√24 to 1 decimal place? (a) 4.9 (b) 5.1 (c) 5.0 (d) 4.8
  11. 11.√45 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 6.9 (d) 7.0
  12. 12.Best estimate of 4077 ÷ 43? (a) 1020 (b) 10200 (c) 102
  13. 13.√23 to 1 decimal place? (a) 5.0 (b) 4.8 (c) 5.1 (d) 4.9
  14. 14.Best estimate of 6591 ÷ 88? (a) 7300 (b) 73 (c) 730
  15. 15.√44 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 6.7 (d) 6.6
  16. 16.Best estimate of 2673 ÷ 52? (a) 5300 (b) 53 (c) 530
  17. 17.Best estimate of 1433 ÷ 56? (a) 2400 (b) 240 (c) 24
  18. 18.√41 to 1 decimal place? (a) 6.4 (b) 6.7 (c) 6.5 (d) 6.6
  19. 19.Best estimate of 864 ÷ 56? (a) 140 (b) 1400 (c) 14
  20. 20.Best estimate of 6121 ÷ 67? (a) 87 (b) 8700 (c) 870
  21. 21.Best estimate of 1914 ÷ 42? (a) 48 (b) 4800 (c) 480
  22. 22.√22 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.4 (d) 4.5
  23. 23.√43 to 1 decimal place? (a) 6.3 (b) 6.6 (c) 6.4 (d) 6.5
  24. 24.Best estimate of 4998 ÷ 88? (a) 5600 (b) 56 (c) 560
  25. 25.Best estimate of 1502 ÷ 61? (a) 250 (b) 2500 (c) 25
  26. 26.√82 to 1 decimal place? (a) 9.0 (b) 9.2 (c) 9.1 (d) 8.9
  27. 27.√74 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.7 (d) 8.5
  28. 28.√30 to 1 decimal place? (a) 5.4 (b) 5.5 (c) 5.3 (d) 5.2
  29. 29.√55 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.1 (d) 7.4
  30. 30.√50 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 7.0 (d) 6.9
  31. 31.√67 to 1 decimal place? (a) 8.2 (b) 8.4 (c) 8.5 (d) 8.3
  32. 32.√69 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.5 (d) 8.4
  33. 33.√58 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.7 (d) 7.6
  34. 34.√20 to 1 decimal place? (a) 4.7 (b) 4.6 (c) 4.8 (d) 4.5
  35. 35.√92 to 1 decimal place? (a) 9.8 (b) 9.6 (c) 9.7 (d) 9.9
  36. 36.√89 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.4 (d) 9.3
  37. 37.Best estimate of 2497 ÷ 38? (a) 6200 (b) 62 (c) 620
  38. 38.Best estimate of 2474 ÷ 86? (a) 270 (b) 27 (c) 2700
  39. 39.√42 to 1 decimal place? (a) 6.6 (b) 6.8 (c) 6.5 (d) 6.7
  40. 40.Best estimate of 2250 ÷ 32? (a) 750 (b) 7500 (c) 75

Answer key

  1. 30
  2. 39
  3. 9.9
  4. 93
  5. 5.1
  6. 76
  7. 42
  8. 90
  9. 7.1
  10. 4.9
  11. 6.7
  12. 102
  13. 4.8
  14. 73
  15. 6.6
  16. 53
  17. 24
  18. 6.4
  19. 14
  20. 87
  21. 48
  22. 4.7
  23. 6.6
  24. 56
  25. 25
  26. 9.1
  27. 8.6
  28. 5.5
  29. 7.4
  30. 7.1
  31. 8.2
  32. 8.3
  33. 7.6
  34. 4.5
  35. 9.6
  36. 9.4
  37. 62
  38. 27
  39. 6.5
  40. 75

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