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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 900 · 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.√26 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.4 (d) 5.1
  2. 2.√44 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.8 (d) 6.7
  3. 3.Best estimate of 3927 ÷ 52? (a) 790 (b) 79 (c) 7900
  4. 4.√89 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.2 (d) 9.1
  5. 5.Best estimate of 1878 ÷ 87? (a) 210 (b) 2100 (c) 21
  6. 6.Best estimate of 7367 ÷ 78? (a) 92 (b) 920 (c) 9200
  7. 7.√55 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.1 (d) 7.4
  8. 8.Best estimate of 2984 ÷ 66? (a) 4300 (b) 430 (c) 43
  9. 9.√63 to 1 decimal place? (a) 7.8 (b) 8.0 (c) 7.7 (d) 7.9
  10. 10.√56 to 1 decimal place? (a) 7.5 (b) 7.8 (c) 7.6 (d) 7.7
  11. 11.Best estimate of 2398 ÷ 33? (a) 8000 (b) 80 (c) 800
  12. 12.Best estimate of 2566 ÷ 32? (a) 86 (b) 860 (c) 8600
  13. 13.√50 to 1 decimal place? (a) 7.1 (b) 6.9 (c) 7.0 (d) 6.8
  14. 14.Best estimate of 1283 ÷ 89? (a) 140 (b) 14 (c) 1400
  15. 15.Best estimate of 1362 ÷ 59? (a) 23 (b) 230 (c) 2300
  16. 16.√90 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.6 (d) 9.5
  17. 17.Best estimate of 2272 ÷ 29? (a) 7600 (b) 76 (c) 760
  18. 18.Best estimate of 7225 ÷ 86? (a) 800 (b) 80 (c) 8000
  19. 19.Best estimate of 4895 ÷ 73? (a) 70 (b) 700 (c) 7000
  20. 20.Best estimate of 1076 ÷ 79? (a) 1300 (b) 13 (c) 130
  21. 21.√66 to 1 decimal place? (a) 7.9 (b) 7.8 (c) 8.1 (d) 8.0
  22. 22.Best estimate of 1779 ÷ 44? (a) 44 (b) 4400 (c) 440
  23. 23.Best estimate of 2164 ÷ 56? (a) 36 (b) 3600 (c) 360
  24. 24.√51 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.0 (d) 6.9
  25. 25.√31 to 1 decimal place? (a) 5.7 (b) 5.8 (c) 5.6 (d) 5.9
  26. 26.Best estimate of 2089 ÷ 49? (a) 420 (b) 4200 (c) 42
  27. 27.Best estimate of 2514 ÷ 64? (a) 4200 (b) 420 (c) 42
  28. 28.√96 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.8 (d) 9.9
  29. 29.√28 to 1 decimal place? (a) 5.1 (b) 5.4 (c) 5.3 (d) 5.2
  30. 30.Best estimate of 6907 ÷ 86? (a) 77 (b) 7700 (c) 770
  31. 31.Best estimate of 709 ÷ 52? (a) 140 (b) 1400 (c) 14
  32. 32.Best estimate of 1265 ÷ 33? (a) 4200 (b) 420 (c) 42
  33. 33.Best estimate of 5102 ÷ 76? (a) 6400 (b) 640 (c) 64
  34. 34.Best estimate of 3154 ÷ 69? (a) 450 (b) 4500 (c) 45
  35. 35.Best estimate of 3944 ÷ 76? (a) 4900 (b) 49 (c) 490
  36. 36.Best estimate of 6453 ÷ 81? (a) 8100 (b) 81 (c) 810
  37. 37.Best estimate of 1226 ÷ 36? (a) 3100 (b) 310 (c) 31
  38. 38.√45 to 1 decimal place? (a) 6.4 (b) 6.6 (c) 6.5 (d) 6.7
  39. 39.Best estimate of 1546 ÷ 23? (a) 770 (b) 77 (c) 7700
  40. 40.Best estimate of 2899 ÷ 67? (a) 41 (b) 4100 (c) 410

Answer key

  1. 5.1
  2. 6.6
  3. 79
  4. 9.4
  5. 21
  6. 92
  7. 7.4
  8. 43
  9. 7.9
  10. 7.5
  11. 80
  12. 86
  13. 7.1
  14. 14
  15. 23
  16. 9.5
  17. 76
  18. 80
  19. 70
  20. 13
  21. 8.1
  22. 44
  23. 36
  24. 7.1
  25. 5.6
  26. 42
  27. 42
  28. 9.8
  29. 5.3
  30. 77
  31. 14
  32. 42
  33. 64
  34. 45
  35. 49
  36. 81
  37. 31
  38. 6.7
  39. 77
  40. 41

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