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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 484 · 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 1172 ÷ 89? (a) 13 (b) 130 (c) 1300
  2. 2.√70 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.2 (d) 8.1
  3. 3.Best estimate of 1688 ÷ 24? (a) 84 (b) 840 (c) 8400
  4. 4.√40 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.1 (d) 6.0
  5. 5.√21 to 1 decimal place? (a) 4.5 (b) 4.4 (c) 4.3 (d) 4.6
  6. 6.√63 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 7.7 (d) 7.6
  7. 7.√82 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.0 (d) 8.9
  8. 8.√58 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.8 (d) 7.9
  9. 9.√77 to 1 decimal place? (a) 9.0 (b) 8.7 (c) 8.8 (d) 8.9
  10. 10.√48 to 1 decimal place? (a) 7.0 (b) 6.8 (c) 7.1 (d) 6.9
  11. 11.Best estimate of 1136 ÷ 36? (a) 280 (b) 2800 (c) 28
  12. 12.Best estimate of 1087 ÷ 51? (a) 22 (b) 220 (c) 2200
  13. 13.√23 to 1 decimal place? (a) 4.8 (b) 4.6 (c) 4.7 (d) 4.9
  14. 14.Best estimate of 1524 ÷ 47? (a) 3000 (b) 300 (c) 30
  15. 15.√65 to 1 decimal place? (a) 8.1 (b) 7.9 (c) 7.8 (d) 8.0
  16. 16.√55 to 1 decimal place? (a) 7.6 (b) 7.3 (c) 7.5 (d) 7.4
  17. 17.Best estimate of 991 ÷ 34? (a) 330 (b) 3300 (c) 33
  18. 18.Best estimate of 1862 ÷ 23? (a) 93 (b) 9300 (c) 930
  19. 19.√79 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.0 (d) 8.9
  20. 20.√34 to 1 decimal place? (a) 5.7 (b) 6.0 (c) 5.9 (d) 5.8
  21. 21.√67 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 8.2 (d) 7.9
  22. 22.Best estimate of 3862 ÷ 57? (a) 6400 (b) 640 (c) 64
  23. 23.Best estimate of 5561 ÷ 62? (a) 930 (b) 9300 (c) 93
  24. 24.Best estimate of 1535 ÷ 56? (a) 2600 (b) 26 (c) 260
  25. 25.Best estimate of 1486 ÷ 39? (a) 370 (b) 3700 (c) 37
  26. 26.√27 to 1 decimal place? (a) 4.9 (b) 5.2 (c) 5.1 (d) 5.0
  27. 27.Best estimate of 2791 ÷ 42? (a) 70 (b) 7000 (c) 700
  28. 28.Best estimate of 1382 ÷ 76? (a) 17 (b) 170 (c) 1700
  29. 29.Best estimate of 2542 ÷ 29? (a) 8500 (b) 850 (c) 85
  30. 30.Best estimate of 5896 ÷ 71? (a) 84 (b) 840 (c) 8400
  31. 31.Best estimate of 2436 ÷ 81? (a) 3000 (b) 300 (c) 30
  32. 32.√69 to 1 decimal place? (a) 8.3 (b) 8.6 (c) 8.5 (d) 8.4
  33. 33.√96 to 1 decimal place? (a) 9.9 (b) 9.7 (c) 9.8 (d) 9.6
  34. 34.Best estimate of 1447 ÷ 26? (a) 480 (b) 4800 (c) 48
  35. 35.Best estimate of 2899 ÷ 86? (a) 3200 (b) 32 (c) 320
  36. 36.Best estimate of 686 ÷ 29? (a) 23 (b) 2300 (c) 230
  37. 37.Best estimate of 1541 ÷ 88? (a) 170 (b) 1700 (c) 17
  38. 38.Best estimate of 778 ÷ 36? (a) 1900 (b) 19 (c) 190
  39. 39.√61 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 7.6 (d) 7.9
  40. 40.√46 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 7.0 (d) 6.9

Answer key

  1. 13
  2. 8.4
  3. 84
  4. 6.3
  5. 4.6
  6. 7.9
  7. 9.1
  8. 7.6
  9. 8.8
  10. 6.9
  11. 28
  12. 22
  13. 4.8
  14. 30
  15. 8.1
  16. 7.4
  17. 33
  18. 93
  19. 8.9
  20. 5.8
  21. 8.2
  22. 64
  23. 93
  24. 26
  25. 37
  26. 5.2
  27. 70
  28. 17
  29. 85
  30. 84
  31. 30
  32. 8.3
  33. 9.8
  34. 48
  35. 32
  36. 23
  37. 17
  38. 19
  39. 7.8
  40. 6.8

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