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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 427 · 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.√41 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.1 (d) 6.2
  2. 2.√31 to 1 decimal place? (a) 5.6 (b) 5.4 (c) 5.3 (d) 5.5
  3. 3.Best estimate of 3039 ÷ 66? (a) 43 (b) 430 (c) 4300
  4. 4.√43 to 1 decimal place? (a) 6.9 (b) 6.7 (c) 6.8 (d) 6.6
  5. 5.√32 to 1 decimal place? (a) 5.8 (b) 5.6 (c) 5.9 (d) 5.7
  6. 6.Best estimate of 2425 ÷ 27? (a) 8100 (b) 810 (c) 81
  7. 7.√34 to 1 decimal place? (a) 5.6 (b) 5.9 (c) 5.8 (d) 5.7
  8. 8.√69 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 8.3 (d) 8.0
  9. 9.Best estimate of 1633 ÷ 68? (a) 2300 (b) 23 (c) 230
  10. 10.Best estimate of 3740 ÷ 77? (a) 470 (b) 47 (c) 4700
  11. 11.√62 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 8.0 (d) 7.9
  12. 12.Best estimate of 684 ÷ 52? (a) 14 (b) 1400 (c) 140
  13. 13.√98 to 1 decimal place? (a) 9.7 (b) 9.9 (c) 9.8 (d) 9.6
  14. 14.Best estimate of 6436 ÷ 74? (a) 92 (b) 9200 (c) 920
  15. 15.√94 to 1 decimal place? (a) 9.9 (b) 10.0 (c) 9.7 (d) 9.8
  16. 16.Best estimate of 539 ÷ 29? (a) 1800 (b) 180 (c) 18
  17. 17.Best estimate of 2687 ÷ 66? (a) 380 (b) 38 (c) 3800
  18. 18.Best estimate of 5304 ÷ 78? (a) 66 (b) 660 (c) 6600
  19. 19.Best estimate of 6410 ÷ 82? (a) 80 (b) 800 (c) 8000
  20. 20.√79 to 1 decimal place? (a) 8.9 (b) 8.7 (c) 9.0 (d) 8.8
  21. 21.√21 to 1 decimal place? (a) 4.8 (b) 4.9 (c) 4.7 (d) 4.6
  22. 22.Best estimate of 1150 ÷ 48? (a) 2300 (b) 23 (c) 230
  23. 23.√92 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.5 (d) 9.7
  24. 24.Best estimate of 1864 ÷ 28? (a) 6200 (b) 62 (c) 620
  25. 25.√61 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 8.1 (d) 8.0
  26. 26.√82 to 1 decimal place? (a) 9.2 (b) 8.9 (c) 9.0 (d) 9.1
  27. 27.Best estimate of 2099 ÷ 37? (a) 520 (b) 5200 (c) 52
  28. 28.√40 to 1 decimal place? (a) 6.3 (b) 6.5 (c) 6.2 (d) 6.4
  29. 29.Best estimate of 2801 ÷ 46? (a) 5600 (b) 560 (c) 56
  30. 30.√77 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.7 (d) 8.8
  31. 31.Best estimate of 1071 ÷ 26? (a) 36 (b) 360 (c) 3600
  32. 32.Best estimate of 3737 ÷ 61? (a) 620 (b) 62 (c) 6200
  33. 33.Best estimate of 612 ÷ 22? (a) 310 (b) 3100 (c) 31
  34. 34.√38 to 1 decimal place? (a) 6.5 (b) 6.4 (c) 6.2 (d) 6.3
  35. 35.Best estimate of 1113 ÷ 32? (a) 37 (b) 370 (c) 3700
  36. 36.√58 to 1 decimal place? (a) 7.6 (b) 7.5 (c) 7.8 (d) 7.7
  37. 37.Best estimate of 2058 ÷ 79? (a) 2600 (b) 260 (c) 26
  38. 38.√30 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.5 (d) 5.8
  39. 39.Best estimate of 7226 ÷ 82? (a) 900 (b) 9000 (c) 90
  40. 40.Best estimate of 398 ÷ 24? (a) 200 (b) 2000 (c) 20

Answer key

  1. 6.4
  2. 5.6
  3. 43
  4. 6.6
  5. 5.7
  6. 81
  7. 5.8
  8. 8.3
  9. 23
  10. 47
  11. 7.9
  12. 14
  13. 9.9
  14. 92
  15. 9.7
  16. 18
  17. 38
  18. 66
  19. 80
  20. 8.9
  21. 4.6
  22. 23
  23. 9.6
  24. 62
  25. 7.8
  26. 9.1
  27. 52
  28. 6.3
  29. 56
  30. 8.8
  31. 36
  32. 62
  33. 31
  34. 6.2
  35. 37
  36. 7.6
  37. 26
  38. 5.5
  39. 90
  40. 20

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