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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 795 · 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.√65 to 1 decimal place? (a) 7.8 (b) 8.1 (c) 7.9 (d) 8.0
  2. 2.Best estimate of 3151 ÷ 76? (a) 3900 (b) 39 (c) 390
  3. 3.√20 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.4 (d) 4.5
  4. 4.Best estimate of 4030 ÷ 82? (a) 500 (b) 50 (c) 5000
  5. 5.Best estimate of 3558 ÷ 66? (a) 5100 (b) 510 (c) 51
  6. 6.Best estimate of 1791 ÷ 77? (a) 220 (b) 2200 (c) 22
  7. 7.Best estimate of 2142 ÷ 33? (a) 710 (b) 7100 (c) 71
  8. 8.Best estimate of 444 ÷ 26? (a) 1500 (b) 15 (c) 150
  9. 9.Best estimate of 5353 ÷ 62? (a) 890 (b) 8900 (c) 89
  10. 10.Best estimate of 1747 ÷ 26? (a) 5800 (b) 58 (c) 580
  11. 11.Best estimate of 4450 ÷ 78? (a) 560 (b) 56 (c) 5600
  12. 12.√48 to 1 decimal place? (a) 6.8 (b) 6.7 (c) 6.9 (d) 7.0
  13. 13.√42 to 1 decimal place? (a) 6.6 (b) 6.4 (c) 6.7 (d) 6.5
  14. 14.Best estimate of 4171 ÷ 47? (a) 830 (b) 8300 (c) 83
  15. 15.Best estimate of 1648 ÷ 39? (a) 4100 (b) 410 (c) 41
  16. 16.√43 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 6.9 (d) 6.6
  17. 17.Best estimate of 6470 ÷ 76? (a) 810 (b) 8100 (c) 81
  18. 18.Best estimate of 2393 ÷ 43? (a) 6000 (b) 600 (c) 60
  19. 19.√34 to 1 decimal place? (a) 5.8 (b) 6.1 (c) 6.0 (d) 5.9
  20. 20.Best estimate of 1268 ÷ 46? (a) 250 (b) 25 (c) 2500
  21. 21.√90 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.7 (d) 9.4
  22. 22.Best estimate of 1373 ÷ 41? (a) 34 (b) 3400 (c) 340
  23. 23.Best estimate of 2151 ÷ 72? (a) 31 (b) 310 (c) 3100
  24. 24.Best estimate of 1087 ÷ 36? (a) 270 (b) 2700 (c) 27
  25. 25.Best estimate of 3065 ÷ 61? (a) 51 (b) 510 (c) 5100
  26. 26.√58 to 1 decimal place? (a) 7.4 (b) 7.6 (c) 7.7 (d) 7.5
  27. 27.Best estimate of 2908 ÷ 67? (a) 4200 (b) 42 (c) 420
  28. 28.Best estimate of 1464 ÷ 46? (a) 2900 (b) 29 (c) 290
  29. 29.√51 to 1 decimal place? (a) 7.3 (b) 7.2 (c) 7.1 (d) 7.4
  30. 30.√74 to 1 decimal place? (a) 8.9 (b) 8.7 (c) 8.8 (d) 8.6
  31. 31.√82 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.1 (d) 9.2
  32. 32.√59 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 7.9 (d) 7.6
  33. 33.Best estimate of 3568 ÷ 47? (a) 7100 (b) 71 (c) 710
  34. 34.√30 to 1 decimal place? (a) 5.5 (b) 5.8 (c) 5.7 (d) 5.6
  35. 35.√86 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.5 (d) 9.3
  36. 36.√85 to 1 decimal place? (a) 9.1 (b) 8.9 (c) 9.0 (d) 9.2
  37. 37.Best estimate of 1347 ÷ 23? (a) 67 (b) 6700 (c) 670
  38. 38.Best estimate of 1162 ÷ 83? (a) 1500 (b) 150 (c) 15
  39. 39.√98 to 1 decimal place? (a) 9.8 (b) 10.1 (c) 10.0 (d) 9.9
  40. 40.√46 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 6.9 (d) 7.0

Answer key

  1. 8.1
  2. 39
  3. 4.5
  4. 50
  5. 51
  6. 22
  7. 71
  8. 15
  9. 89
  10. 58
  11. 56
  12. 6.9
  13. 6.5
  14. 83
  15. 41
  16. 6.6
  17. 81
  18. 60
  19. 5.8
  20. 25
  21. 9.5
  22. 34
  23. 31
  24. 27
  25. 51
  26. 7.6
  27. 42
  28. 29
  29. 7.1
  30. 8.6
  31. 9.1
  32. 7.7
  33. 71
  34. 5.5
  35. 9.3
  36. 9.2
  37. 67
  38. 15
  39. 9.9
  40. 6.8

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