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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 975 · 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.Best estimate of 1348 ÷ 77? (a) 170 (b) 17 (c) 1700
  2. 2.Best estimate of 863 ÷ 56? (a) 140 (b) 14 (c) 1400
  3. 3.Best estimate of 4437 ÷ 54? (a) 8900 (b) 89 (c) 890
  4. 4.√45 to 1 decimal place? (a) 6.9 (b) 6.7 (c) 6.6 (d) 6.8
  5. 5.√56 to 1 decimal place? (a) 7.5 (b) 7.3 (c) 7.4 (d) 7.2
  6. 6.Best estimate of 2521 ÷ 63? (a) 4200 (b) 420 (c) 42
  7. 7.Best estimate of 2804 ÷ 66? (a) 400 (b) 4000 (c) 40
  8. 8.√69 to 1 decimal place? (a) 8.0 (b) 8.2 (c) 8.1 (d) 8.3
  9. 9.Best estimate of 1011 ÷ 26? (a) 34 (b) 3400 (c) 340
  10. 10.√88 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.3 (d) 9.6
  11. 11.Best estimate of 2873 ÷ 31? (a) 960 (b) 96 (c) 9600
  12. 12.Best estimate of 3299 ÷ 54? (a) 66 (b) 660 (c) 6600
  13. 13.√48 to 1 decimal place? (a) 7.1 (b) 6.9 (c) 7.2 (d) 7.0
  14. 14.√70 to 1 decimal place? (a) 8.7 (b) 8.4 (c) 8.6 (d) 8.5
  15. 15.Best estimate of 1462 ÷ 83? (a) 180 (b) 1800 (c) 18
  16. 16.√66 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.1 (d) 8.0
  17. 17.Best estimate of 2407 ÷ 27? (a) 800 (b) 80 (c) 8000
  18. 18.Best estimate of 2894 ÷ 32? (a) 960 (b) 96 (c) 9600
  19. 19.√72 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.8 (d) 8.5
  20. 20.Best estimate of 1915 ÷ 22? (a) 96 (b) 960 (c) 9600
  21. 21.Best estimate of 280 ÷ 23? (a) 140 (b) 14 (c) 1400
  22. 22.Best estimate of 2795 ÷ 34? (a) 9300 (b) 930 (c) 93
  23. 23.Best estimate of 1858 ÷ 37? (a) 460 (b) 4600 (c) 46
  24. 24.Best estimate of 1093 ÷ 58? (a) 1800 (b) 180 (c) 18
  25. 25.√55 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.7 (d) 7.5
  26. 26.Best estimate of 3860 ÷ 54? (a) 7700 (b) 77 (c) 770
  27. 27.Best estimate of 5963 ÷ 76? (a) 750 (b) 7500 (c) 75
  28. 28.√20 to 1 decimal place? (a) 4.8 (b) 4.5 (c) 4.7 (d) 4.6
  29. 29.Best estimate of 1588 ÷ 69? (a) 230 (b) 23 (c) 2300
  30. 30.√59 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 8.0 (d) 7.9
  31. 31.√34 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 6.1 (d) 5.8
  32. 32.Best estimate of 605 ÷ 47? (a) 1200 (b) 12 (c) 120
  33. 33.Best estimate of 3223 ÷ 86? (a) 3600 (b) 36 (c) 360
  34. 34.Best estimate of 1589 ÷ 64? (a) 260 (b) 2600 (c) 26
  35. 35.Best estimate of 1165 ÷ 37? (a) 29 (b) 2900 (c) 290
  36. 36.Best estimate of 1538 ÷ 64? (a) 2600 (b) 26 (c) 260
  37. 37.Best estimate of 6406 ÷ 71? (a) 92 (b) 9200 (c) 920
  38. 38.Best estimate of 546 ÷ 24? (a) 270 (b) 2700 (c) 27
  39. 39.Best estimate of 6041 ÷ 72? (a) 8600 (b) 860 (c) 86
  40. 40.Best estimate of 1982 ÷ 66? (a) 280 (b) 2800 (c) 28

Answer key

  1. 17
  2. 14
  3. 89
  4. 6.7
  5. 7.5
  6. 42
  7. 40
  8. 8.3
  9. 34
  10. 9.4
  11. 96
  12. 66
  13. 6.9
  14. 8.4
  15. 18
  16. 8.1
  17. 80
  18. 96
  19. 8.5
  20. 96
  21. 14
  22. 93
  23. 46
  24. 18
  25. 7.4
  26. 77
  27. 75
  28. 4.5
  29. 23
  30. 7.7
  31. 5.8
  32. 12
  33. 36
  34. 26
  35. 29
  36. 26
  37. 92
  38. 27
  39. 86
  40. 28

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