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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 971 · 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.√79 to 1 decimal place? (a) 8.9 (b) 9.2 (c) 9.1 (d) 9.0
  2. 2.√32 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.7 (d) 5.4
  3. 3.Best estimate of 825 ÷ 32? (a) 28 (b) 280 (c) 2800
  4. 4.√35 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.9 (d) 5.8
  5. 5.√52 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.4 (d) 7.1
  6. 6.Best estimate of 7025 ÷ 79? (a) 88 (b) 8800 (c) 880
  7. 7.√65 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 8.2 (d) 8.3
  8. 8.√94 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 10.0 (d) 9.9
  9. 9.Best estimate of 5240 ÷ 66? (a) 7500 (b) 750 (c) 75
  10. 10.√31 to 1 decimal place? (a) 5.5 (b) 5.7 (c) 5.4 (d) 5.6
  11. 11.√34 to 1 decimal place? (a) 6.1 (b) 5.9 (c) 5.8 (d) 6.0
  12. 12.√88 to 1 decimal place? (a) 9.3 (b) 9.5 (c) 9.4 (d) 9.6
  13. 13.√45 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.7 (d) 6.4
  14. 14.Best estimate of 1943 ÷ 78? (a) 2400 (b) 240 (c) 24
  15. 15.√27 to 1 decimal place? (a) 5.3 (b) 5.2 (c) 5.0 (d) 5.1
  16. 16.Best estimate of 7236 ÷ 86? (a) 800 (b) 8000 (c) 80
  17. 17.√24 to 1 decimal place? (a) 4.7 (b) 4.9 (c) 4.8 (d) 4.6
  18. 18.Best estimate of 1050 ÷ 36? (a) 2600 (b) 260 (c) 26
  19. 19.Best estimate of 3516 ÷ 69? (a) 500 (b) 5000 (c) 50
  20. 20.√82 to 1 decimal place? (a) 9.4 (b) 9.2 (c) 9.3 (d) 9.1
  21. 21.Best estimate of 5414 ÷ 84? (a) 680 (b) 6800 (c) 68
  22. 22.Best estimate of 2241 ÷ 37? (a) 560 (b) 5600 (c) 56
  23. 23.√89 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.3 (d) 9.6
  24. 24.Best estimate of 4839 ÷ 66? (a) 690 (b) 6900 (c) 69
  25. 25.√96 to 1 decimal place? (a) 9.9 (b) 10.0 (c) 10.1 (d) 9.8
  26. 26.√43 to 1 decimal place? (a) 6.3 (b) 6.5 (c) 6.4 (d) 6.6
  27. 27.Best estimate of 2270 ÷ 38? (a) 5700 (b) 570 (c) 57
  28. 28.Best estimate of 1057 ÷ 66? (a) 1500 (b) 15 (c) 150
  29. 29.Best estimate of 1407 ÷ 24? (a) 700 (b) 7000 (c) 70
  30. 30.Best estimate of 1108 ÷ 81? (a) 1400 (b) 140 (c) 14
  31. 31.√58 to 1 decimal place? (a) 7.5 (b) 7.3 (c) 7.6 (d) 7.4
  32. 32.Best estimate of 3765 ÷ 78? (a) 4700 (b) 470 (c) 47
  33. 33.Best estimate of 674 ÷ 27? (a) 2200 (b) 22 (c) 220
  34. 34.√67 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.1 (d) 8.4
  35. 35.Best estimate of 760 ÷ 33? (a) 250 (b) 2500 (c) 25
  36. 36.Best estimate of 1149 ÷ 41? (a) 2900 (b) 29 (c) 290
  37. 37.Best estimate of 3668 ÷ 78? (a) 4600 (b) 46 (c) 460
  38. 38.√28 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.1 (d) 5.0
  39. 39.Best estimate of 4330 ÷ 72? (a) 620 (b) 6200 (c) 62
  40. 40.Best estimate of 808 ÷ 37? (a) 20 (b) 200 (c) 2000

Answer key

  1. 8.9
  2. 5.7
  3. 28
  4. 5.9
  5. 7.2
  6. 88
  7. 8.1
  8. 9.7
  9. 75
  10. 5.6
  11. 5.8
  12. 9.4
  13. 6.7
  14. 24
  15. 5.2
  16. 80
  17. 4.9
  18. 26
  19. 50
  20. 9.1
  21. 68
  22. 56
  23. 9.4
  24. 69
  25. 9.8
  26. 6.6
  27. 57
  28. 15
  29. 70
  30. 14
  31. 7.6
  32. 47
  33. 22
  34. 8.2
  35. 25
  36. 29
  37. 46
  38. 5.3
  39. 62
  40. 20

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