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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 790 · 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.√63 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.1 (d) 7.8
  2. 2.Best estimate of 1080 ÷ 31? (a) 360 (b) 3600 (c) 36
  3. 3.√84 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 8.9 (d) 9.2
  4. 4.√80 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 8.7 (d) 8.9
  5. 5.√26 to 1 decimal place? (a) 5.1 (b) 5.2 (c) 5.3 (d) 5.0
  6. 6.Best estimate of 2076 ÷ 63? (a) 3500 (b) 350 (c) 35
  7. 7.Best estimate of 5616 ÷ 77? (a) 700 (b) 70 (c) 7000
  8. 8.√90 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.4 (d) 9.3
  9. 9.√94 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 9.7 (d) 10.0
  10. 10.Best estimate of 2392 ÷ 63? (a) 400 (b) 4000 (c) 40
  11. 11.Best estimate of 4389 ÷ 48? (a) 88 (b) 8800 (c) 880
  12. 12.Best estimate of 1437 ÷ 34? (a) 480 (b) 4800 (c) 48
  13. 13.Best estimate of 6550 ÷ 87? (a) 730 (b) 73 (c) 7300
  14. 14.Best estimate of 4515 ÷ 52? (a) 90 (b) 900 (c) 9000
  15. 15.Best estimate of 2970 ÷ 61? (a) 5000 (b) 500 (c) 50
  16. 16.Best estimate of 1171 ÷ 71? (a) 1700 (b) 170 (c) 17
  17. 17.Best estimate of 537 ÷ 26? (a) 18 (b) 180 (c) 1800
  18. 18.√37 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 6.0 (d) 6.3
  19. 19.Best estimate of 1723 ÷ 34? (a) 5700 (b) 57 (c) 570
  20. 20.Best estimate of 6300 ÷ 72? (a) 9000 (b) 90 (c) 900
  21. 21.Best estimate of 1585 ÷ 21? (a) 79 (b) 7900 (c) 790
  22. 22.√24 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 4.7 (d) 4.8
  23. 23.Best estimate of 2823 ÷ 53? (a) 560 (b) 56 (c) 5600
  24. 24.√82 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.1 (d) 9.4
  25. 25.Best estimate of 788 ÷ 36? (a) 2000 (b) 20 (c) 200
  26. 26.Best estimate of 6477 ÷ 89? (a) 720 (b) 7200 (c) 72
  27. 27.√21 to 1 decimal place? (a) 4.8 (b) 4.5 (c) 4.6 (d) 4.7
  28. 28.√38 to 1 decimal place? (a) 6.4 (b) 6.2 (c) 6.3 (d) 6.5
  29. 29.Best estimate of 2277 ÷ 34? (a) 76 (b) 760 (c) 7600
  30. 30.√98 to 1 decimal place? (a) 9.9 (b) 9.6 (c) 9.7 (d) 9.8
  31. 31.√61 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 8.0 (d) 7.7
  32. 32.Best estimate of 1304 ÷ 82? (a) 1600 (b) 16 (c) 160
  33. 33.Best estimate of 3973 ÷ 62? (a) 660 (b) 66 (c) 6600
  34. 34.Best estimate of 341 ÷ 22? (a) 170 (b) 1700 (c) 17
  35. 35.√62 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 7.8 (d) 7.9
  36. 36.√74 to 1 decimal place? (a) 8.4 (b) 8.6 (c) 8.5 (d) 8.7
  37. 37.Best estimate of 1263 ÷ 32? (a) 42 (b) 420 (c) 4200
  38. 38.Best estimate of 4395 ÷ 69? (a) 6300 (b) 63 (c) 630
  39. 39.Best estimate of 2269 ÷ 66? (a) 3200 (b) 320 (c) 32
  40. 40.Best estimate of 3351 ÷ 57? (a) 56 (b) 560 (c) 5600

Answer key

  1. 7.9
  2. 36
  3. 9.2
  4. 8.9
  5. 5.1
  6. 35
  7. 70
  8. 9.5
  9. 9.7
  10. 40
  11. 88
  12. 48
  13. 73
  14. 90
  15. 50
  16. 17
  17. 18
  18. 6.1
  19. 57
  20. 90
  21. 79
  22. 4.9
  23. 56
  24. 9.1
  25. 20
  26. 72
  27. 4.6
  28. 6.2
  29. 76
  30. 9.9
  31. 7.8
  32. 16
  33. 66
  34. 17
  35. 7.9
  36. 8.6
  37. 42
  38. 63
  39. 32
  40. 56

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