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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 246 · 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.√88 to 1 decimal place? (a) 9.5 (b) 9.2 (c) 9.3 (d) 9.4
  2. 2.√94 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.7 (d) 9.5
  3. 3.Best estimate of 837 ÷ 68? (a) 1200 (b) 12 (c) 120
  4. 4.√58 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.5 (d) 7.6
  5. 5.Best estimate of 5190 ÷ 78? (a) 650 (b) 65 (c) 6500
  6. 6.√96 to 1 decimal place? (a) 9.7 (b) 9.5 (c) 9.8 (d) 9.6
  7. 7.Best estimate of 1588 ÷ 36? (a) 40 (b) 400 (c) 4000
  8. 8.Best estimate of 1036 ÷ 27? (a) 35 (b) 350 (c) 3500
  9. 9.Best estimate of 1440 ÷ 56? (a) 2400 (b) 24 (c) 240
  10. 10.√51 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 7.1 (d) 7.0
  11. 11.√28 to 1 decimal place? (a) 5.1 (b) 5.0 (c) 5.2 (d) 5.3
  12. 12.√40 to 1 decimal place? (a) 6.4 (b) 6.2 (c) 6.3 (d) 6.5
  13. 13.Best estimate of 4040 ÷ 79? (a) 51 (b) 510 (c) 5100
  14. 14.Best estimate of 1587 ÷ 87? (a) 1800 (b) 180 (c) 18
  15. 15.Best estimate of 3913 ÷ 56? (a) 6500 (b) 650 (c) 65
  16. 16.Best estimate of 2529 ÷ 47? (a) 510 (b) 5100 (c) 51
  17. 17.Best estimate of 3690 ÷ 81? (a) 4600 (b) 46 (c) 460
  18. 18.√74 to 1 decimal place? (a) 8.8 (b) 8.6 (c) 8.5 (d) 8.7
  19. 19.Best estimate of 1405 ÷ 22? (a) 700 (b) 7000 (c) 70
  20. 20.√38 to 1 decimal place? (a) 6.4 (b) 6.1 (c) 6.2 (d) 6.3
  21. 21.√59 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.9 (d) 7.8
  22. 22.√24 to 1 decimal place? (a) 5.0 (b) 4.8 (c) 4.9 (d) 4.7
  23. 23.√45 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 6.6 (d) 6.7
  24. 24.√48 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 6.9 (d) 7.0
  25. 25.√76 to 1 decimal place? (a) 8.5 (b) 8.7 (c) 8.6 (d) 8.4
  26. 26.Best estimate of 1620 ÷ 26? (a) 5400 (b) 540 (c) 54
  27. 27.√69 to 1 decimal place? (a) 8.3 (b) 8.5 (c) 8.4 (d) 8.6
  28. 28.√82 to 1 decimal place? (a) 9.1 (b) 8.9 (c) 8.8 (d) 9.0
  29. 29.Best estimate of 1356 ÷ 52? (a) 27 (b) 2700 (c) 270
  30. 30.Best estimate of 3804 ÷ 62? (a) 63 (b) 6300 (c) 630
  31. 31.√79 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 8.9 (d) 9.1
  32. 32.Best estimate of 3164 ÷ 52? (a) 6300 (b) 63 (c) 630
  33. 33.√84 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.5 (d) 9.4
  34. 34.Best estimate of 5395 ÷ 78? (a) 670 (b) 6700 (c) 67
  35. 35.√50 to 1 decimal place? (a) 7.3 (b) 7.0 (c) 7.2 (d) 7.1
  36. 36.√41 to 1 decimal place? (a) 6.3 (b) 6.5 (c) 6.2 (d) 6.4
  37. 37.Best estimate of 399 ÷ 21? (a) 200 (b) 20 (c) 2000
  38. 38.√83 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 9.1 (d) 8.9
  39. 39.√92 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.5 (d) 9.8
  40. 40.√77 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.8 (d) 8.5

Answer key

  1. 9.4
  2. 9.7
  3. 12
  4. 7.6
  5. 65
  6. 9.8
  7. 40
  8. 35
  9. 24
  10. 7.1
  11. 5.3
  12. 6.3
  13. 51
  14. 18
  15. 65
  16. 51
  17. 46
  18. 8.6
  19. 70
  20. 6.2
  21. 7.7
  22. 4.9
  23. 6.7
  24. 6.9
  25. 8.7
  26. 54
  27. 8.3
  28. 9.1
  29. 27
  30. 63
  31. 8.9
  32. 63
  33. 9.2
  34. 67
  35. 7.1
  36. 6.4
  37. 20
  38. 9.1
  39. 9.6
  40. 8.8

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