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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 414 · 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 1079 ÷ 36? (a) 2700 (b) 270 (c) 27
  2. 2.√50 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 7.4 (d) 7.3
  3. 3.√78 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.7 (d) 8.8
  4. 4.√87 to 1 decimal place? (a) 9.2 (b) 9.4 (c) 9.5 (d) 9.3
  5. 5.Best estimate of 714 ÷ 21? (a) 3600 (b) 360 (c) 36
  6. 6.√65 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.2 (d) 8.1
  7. 7.√40 to 1 decimal place? (a) 6.4 (b) 6.5 (c) 6.3 (d) 6.2
  8. 8.Best estimate of 1030 ÷ 23? (a) 520 (b) 52 (c) 5200
  9. 9.Best estimate of 6631 ÷ 87? (a) 74 (b) 7400 (c) 740
  10. 10.Best estimate of 3843 ÷ 78? (a) 48 (b) 480 (c) 4800
  11. 11.√35 to 1 decimal place? (a) 5.7 (b) 5.8 (c) 5.9 (d) 5.6
  12. 12.Best estimate of 4483 ÷ 49? (a) 900 (b) 90 (c) 9000
  13. 13.√92 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.8 (d) 9.7
  14. 14.√41 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.4 (d) 6.1
  15. 15.Best estimate of 1264 ÷ 27? (a) 420 (b) 42 (c) 4200
  16. 16.√38 to 1 decimal place? (a) 6.5 (b) 6.2 (c) 6.4 (d) 6.3
  17. 17.Best estimate of 2498 ÷ 32? (a) 83 (b) 8300 (c) 830
  18. 18.√29 to 1 decimal place? (a) 5.7 (b) 5.5 (c) 5.6 (d) 5.4
  19. 19.Best estimate of 1652 ÷ 64? (a) 280 (b) 2800 (c) 28
  20. 20.Best estimate of 2870 ÷ 66? (a) 410 (b) 41 (c) 4100
  21. 21.√69 to 1 decimal place? (a) 8.4 (b) 8.6 (c) 8.3 (d) 8.5
  22. 22.√46 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 6.7 (d) 7.0
  23. 23.√70 to 1 decimal place? (a) 8.1 (b) 8.3 (c) 8.4 (d) 8.2
  24. 24.√59 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 7.7 (d) 8.0
  25. 25.Best estimate of 1262 ÷ 46? (a) 2500 (b) 25 (c) 250
  26. 26.√85 to 1 decimal place? (a) 9.2 (b) 8.9 (c) 9.0 (d) 9.1
  27. 27.Best estimate of 2828 ÷ 68? (a) 4000 (b) 40 (c) 400
  28. 28.Best estimate of 1257 ÷ 39? (a) 310 (b) 31 (c) 3100
  29. 29.√94 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.6 (d) 9.4
  30. 30.Best estimate of 5018 ÷ 74? (a) 720 (b) 72 (c) 7200
  31. 31.Best estimate of 1104 ÷ 52? (a) 220 (b) 22 (c) 2200
  32. 32.Best estimate of 3448 ÷ 39? (a) 8600 (b) 86 (c) 860
  33. 33.√27 to 1 decimal place? (a) 5.1 (b) 5.2 (c) 5.4 (d) 5.3
  34. 34.Best estimate of 2477 ÷ 34? (a) 830 (b) 8300 (c) 83
  35. 35.√34 to 1 decimal place? (a) 6.0 (b) 5.8 (c) 5.7 (d) 5.9
  36. 36.√24 to 1 decimal place? (a) 4.7 (b) 5.0 (c) 4.8 (d) 4.9
  37. 37.√96 to 1 decimal place? (a) 10.0 (b) 9.8 (c) 9.7 (d) 9.9
  38. 38.√55 to 1 decimal place? (a) 7.7 (b) 7.4 (c) 7.6 (d) 7.5
  39. 39.Best estimate of 1887 ÷ 32? (a) 63 (b) 630 (c) 6300
  40. 40.Best estimate of 2174 ÷ 78? (a) 27 (b) 270 (c) 2700

Answer key

  1. 27
  2. 7.1
  3. 8.8
  4. 9.3
  5. 36
  6. 8.1
  7. 6.3
  8. 52
  9. 74
  10. 48
  11. 5.9
  12. 90
  13. 9.6
  14. 6.4
  15. 42
  16. 6.2
  17. 83
  18. 5.4
  19. 28
  20. 41
  21. 8.3
  22. 6.8
  23. 8.4
  24. 7.7
  25. 25
  26. 9.2
  27. 40
  28. 31
  29. 9.7
  30. 72
  31. 22
  32. 86
  33. 5.2
  34. 83
  35. 5.8
  36. 4.9
  37. 9.8
  38. 7.4
  39. 63
  40. 27

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