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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 320 · 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 3113 ÷ 78? (a) 3900 (b) 390 (c) 39
  2. 2.Best estimate of 1999 ÷ 39? (a) 50 (b) 5000 (c) 500
  3. 3.Best estimate of 6871 ÷ 84? (a) 86 (b) 8600 (c) 860
  4. 4.Best estimate of 4662 ÷ 89? (a) 5200 (b) 52 (c) 520
  5. 5.Best estimate of 1656 ÷ 24? (a) 830 (b) 83 (c) 8300
  6. 6.√22 to 1 decimal place? (a) 4.4 (b) 4.5 (c) 4.7 (d) 4.6
  7. 7.Best estimate of 554 ÷ 26? (a) 18 (b) 180 (c) 1800
  8. 8.Best estimate of 1411 ÷ 27? (a) 47 (b) 4700 (c) 470
  9. 9.Best estimate of 923 ÷ 42? (a) 23 (b) 2300 (c) 230
  10. 10.Best estimate of 1978 ÷ 37? (a) 490 (b) 4900 (c) 49
  11. 11.Best estimate of 2575 ÷ 39? (a) 6400 (b) 64 (c) 640
  12. 12.√80 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 8.9 (d) 9.1
  13. 13.Best estimate of 6009 ÷ 66? (a) 86 (b) 860 (c) 8600
  14. 14.Best estimate of 2483 ÷ 34? (a) 830 (b) 8300 (c) 83
  15. 15.Best estimate of 5294 ÷ 78? (a) 6600 (b) 660 (c) 66
  16. 16.Best estimate of 3223 ÷ 34? (a) 10700 (b) 1070 (c) 107
  17. 17.√55 to 1 decimal place? (a) 7.2 (b) 7.5 (c) 7.4 (d) 7.3
  18. 18.Best estimate of 2799 ÷ 48? (a) 560 (b) 5600 (c) 56
  19. 19.Best estimate of 441 ÷ 22? (a) 220 (b) 22 (c) 2200
  20. 20.Best estimate of 2510 ÷ 27? (a) 84 (b) 8400 (c) 840
  21. 21.√20 to 1 decimal place? (a) 4.5 (b) 4.4 (c) 4.6 (d) 4.3
  22. 22.√67 to 1 decimal place? (a) 8.1 (b) 7.9 (c) 8.0 (d) 8.2
  23. 23.√40 to 1 decimal place? (a) 6.3 (b) 6.0 (c) 6.2 (d) 6.1
  24. 24.Best estimate of 1838 ÷ 86? (a) 20 (b) 200 (c) 2000
  25. 25.√31 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.5 (d) 5.8
  26. 26.√61 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.5 (d) 7.8
  27. 27.Best estimate of 1080 ÷ 23? (a) 5400 (b) 540 (c) 54
  28. 28.√94 to 1 decimal place? (a) 9.7 (b) 9.5 (c) 9.6 (d) 9.8
  29. 29.Best estimate of 4800 ÷ 56? (a) 80 (b) 8000 (c) 800
  30. 30.√85 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.2 (d) 9.5
  31. 31.Best estimate of 639 ÷ 42? (a) 16 (b) 160 (c) 1600
  32. 32.Best estimate of 6477 ÷ 79? (a) 810 (b) 8100 (c) 81
  33. 33.Best estimate of 1102 ÷ 83? (a) 1400 (b) 140 (c) 14
  34. 34.√79 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 8.9 (d) 8.7
  35. 35.Best estimate of 341 ÷ 22? (a) 170 (b) 1700 (c) 17
  36. 36.√89 to 1 decimal place? (a) 9.2 (b) 9.4 (c) 9.3 (d) 9.1
  37. 37.Best estimate of 2463 ÷ 38? (a) 62 (b) 6200 (c) 620
  38. 38.√34 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.8 (d) 5.5
  39. 39.Best estimate of 1345 ÷ 79? (a) 17 (b) 170 (c) 1700
  40. 40.Best estimate of 6566 ÷ 82? (a) 8200 (b) 82 (c) 820

Answer key

  1. 39
  2. 50
  3. 86
  4. 52
  5. 83
  6. 4.7
  7. 18
  8. 47
  9. 23
  10. 49
  11. 64
  12. 8.9
  13. 86
  14. 83
  15. 66
  16. 107
  17. 7.4
  18. 56
  19. 22
  20. 84
  21. 4.5
  22. 8.2
  23. 6.3
  24. 20
  25. 5.6
  26. 7.8
  27. 54
  28. 9.7
  29. 80
  30. 9.2
  31. 16
  32. 81
  33. 14
  34. 8.9
  35. 17
  36. 9.4
  37. 62
  38. 5.8
  39. 17
  40. 82

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