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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 254 · 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.√37 to 1 decimal place? (a) 6.1 (b) 6.3 (c) 6.2 (d) 6.0
  2. 2.Best estimate of 1117 ÷ 42? (a) 280 (b) 28 (c) 2800
  3. 3.√63 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 7.8 (d) 7.7
  4. 4.√46 to 1 decimal place? (a) 6.6 (b) 6.5 (c) 6.8 (d) 6.7
  5. 5.√88 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.7 (d) 9.4
  6. 6.Best estimate of 2149 ÷ 24? (a) 10700 (b) 1070 (c) 107
  7. 7.Best estimate of 1366 ÷ 39? (a) 340 (b) 34 (c) 3400
  8. 8.Best estimate of 2904 ÷ 68? (a) 41 (b) 4100 (c) 410
  9. 9.Best estimate of 3475 ÷ 63? (a) 58 (b) 5800 (c) 580
  10. 10.Best estimate of 4326 ÷ 62? (a) 72 (b) 7200 (c) 720
  11. 11.Best estimate of 7730 ÷ 84? (a) 970 (b) 97 (c) 9700
  12. 12.√31 to 1 decimal place? (a) 5.4 (b) 5.6 (c) 5.5 (d) 5.3
  13. 13.Best estimate of 1842 ÷ 31? (a) 610 (b) 6100 (c) 61
  14. 14.Best estimate of 1739 ÷ 81? (a) 22 (b) 220 (c) 2200
  15. 15.√34 to 1 decimal place? (a) 5.6 (b) 5.8 (c) 5.5 (d) 5.7
  16. 16.√51 to 1 decimal place? (a) 7.0 (b) 6.9 (c) 7.1 (d) 6.8
  17. 17.√89 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.1 (d) 9.4
  18. 18.Best estimate of 1269 ÷ 36? (a) 320 (b) 3200 (c) 32
  19. 19.Best estimate of 2483 ÷ 31? (a) 8300 (b) 83 (c) 830
  20. 20.√65 to 1 decimal place? (a) 8.0 (b) 8.2 (c) 8.1 (d) 7.9
  21. 21.√77 to 1 decimal place? (a) 8.9 (b) 8.6 (c) 8.8 (d) 8.7
  22. 22.√74 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.4 (d) 8.5
  23. 23.√72 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.5 (d) 8.4
  24. 24.√53 to 1 decimal place? (a) 7.4 (b) 7.2 (c) 7.5 (d) 7.3
  25. 25.Best estimate of 1990 ÷ 37? (a) 500 (b) 5000 (c) 50
  26. 26.Best estimate of 1338 ÷ 61? (a) 2200 (b) 220 (c) 22
  27. 27.√69 to 1 decimal place? (a) 8.5 (b) 8.2 (c) 8.3 (d) 8.4
  28. 28.Best estimate of 3168 ÷ 76? (a) 400 (b) 4000 (c) 40
  29. 29.Best estimate of 902 ÷ 28? (a) 3000 (b) 30 (c) 300
  30. 30.Best estimate of 1090 ÷ 37? (a) 270 (b) 2700 (c) 27
  31. 31.Best estimate of 2632 ÷ 79? (a) 330 (b) 33 (c) 3300
  32. 32.Best estimate of 2591 ÷ 31? (a) 86 (b) 8600 (c) 860
  33. 33.Best estimate of 611 ÷ 26? (a) 200 (b) 20 (c) 2000
  34. 34.Best estimate of 1085 ÷ 46? (a) 22 (b) 220 (c) 2200
  35. 35.√26 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 5.1 (d) 5.2
  36. 36.Best estimate of 1024 ÷ 63? (a) 17 (b) 1700 (c) 170
  37. 37.Best estimate of 3046 ÷ 66? (a) 4400 (b) 440 (c) 44
  38. 38.Best estimate of 3590 ÷ 38? (a) 900 (b) 9000 (c) 90
  39. 39.√55 to 1 decimal place? (a) 7.3 (b) 7.2 (c) 7.1 (d) 7.4
  40. 40.√21 to 1 decimal place? (a) 4.5 (b) 4.4 (c) 4.7 (d) 4.6

Answer key

  1. 6.1
  2. 28
  3. 7.9
  4. 6.8
  5. 9.4
  6. 107
  7. 34
  8. 41
  9. 58
  10. 72
  11. 97
  12. 5.6
  13. 61
  14. 22
  15. 5.8
  16. 7.1
  17. 9.4
  18. 32
  19. 83
  20. 8.1
  21. 8.8
  22. 8.6
  23. 8.5
  24. 7.3
  25. 50
  26. 22
  27. 8.3
  28. 40
  29. 30
  30. 27
  31. 33
  32. 86
  33. 20
  34. 22
  35. 5.1
  36. 17
  37. 44
  38. 90
  39. 7.4
  40. 4.6

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