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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 37 · 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 2373 ÷ 62? (a) 40 (b) 400 (c) 4000
  2. 2.Best estimate of 1938 ÷ 28? (a) 65 (b) 650 (c) 6500
  3. 3.Best estimate of 1701 ÷ 39? (a) 4300 (b) 430 (c) 43
  4. 4.Best estimate of 1488 ÷ 82? (a) 19 (b) 190 (c) 1900
  5. 5.√38 to 1 decimal place? (a) 5.9 (b) 6.2 (c) 6.1 (d) 6.0
  6. 6.Best estimate of 5585 ÷ 76? (a) 7000 (b) 700 (c) 70
  7. 7.Best estimate of 5185 ÷ 58? (a) 86 (b) 8600 (c) 860
  8. 8.Best estimate of 706 ÷ 41? (a) 1800 (b) 180 (c) 18
  9. 9.√92 to 1 decimal place? (a) 9.6 (b) 9.9 (c) 9.8 (d) 9.7
  10. 10.√24 to 1 decimal place? (a) 4.8 (b) 5.0 (c) 4.9 (d) 4.7
  11. 11.√50 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.4 (d) 7.3
  12. 12.Best estimate of 5087 ÷ 62? (a) 850 (b) 8500 (c) 85
  13. 13.Best estimate of 2338 ÷ 74? (a) 33 (b) 330 (c) 3300
  14. 14.Best estimate of 6003 ÷ 74? (a) 860 (b) 86 (c) 8600
  15. 15.Best estimate of 2098 ÷ 32? (a) 70 (b) 7000 (c) 700
  16. 16.√96 to 1 decimal place? (a) 10.1 (b) 9.8 (c) 10.0 (d) 9.9
  17. 17.√61 to 1 decimal place? (a) 7.8 (b) 8.1 (c) 7.9 (d) 8.0
  18. 18.√83 to 1 decimal place? (a) 8.9 (b) 9.1 (c) 9.0 (d) 9.2
  19. 19.√37 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 6.1 (d) 5.8
  20. 20.Best estimate of 2661 ÷ 52? (a) 530 (b) 5300 (c) 53
  21. 21.Best estimate of 3125 ÷ 37? (a) 78 (b) 780 (c) 7800
  22. 22.√59 to 1 decimal place? (a) 7.7 (b) 7.9 (c) 8.0 (d) 7.8
  23. 23.Best estimate of 2060 ÷ 86? (a) 2300 (b) 23 (c) 230
  24. 24.Best estimate of 1678 ÷ 76? (a) 2100 (b) 210 (c) 21
  25. 25.√66 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.1 (d) 8.0
  26. 26.√74 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.8 (d) 8.5
  27. 27.√94 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.5 (d) 9.8
  28. 28.Best estimate of 654 ÷ 41? (a) 1600 (b) 16 (c) 160
  29. 29.Best estimate of 2308 ÷ 38? (a) 580 (b) 58 (c) 5800
  30. 30.√80 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 8.7 (d) 9.0
  31. 31.Best estimate of 1294 ÷ 23? (a) 6500 (b) 65 (c) 650
  32. 32.Best estimate of 1843 ÷ 47? (a) 3700 (b) 37 (c) 370
  33. 33.√70 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.1 (d) 8.4
  34. 34.Best estimate of 666 ÷ 26? (a) 2200 (b) 220 (c) 22
  35. 35.√79 to 1 decimal place? (a) 9.0 (b) 9.2 (c) 9.1 (d) 8.9
  36. 36.Best estimate of 995 ÷ 67? (a) 140 (b) 1400 (c) 14
  37. 37.Best estimate of 5156 ÷ 57? (a) 8600 (b) 860 (c) 86
  38. 38.Best estimate of 1951 ÷ 24? (a) 98 (b) 9800 (c) 980
  39. 39.Best estimate of 1319 ÷ 21? (a) 66 (b) 6600 (c) 660
  40. 40.√21 to 1 decimal place? (a) 4.5 (b) 4.7 (c) 4.8 (d) 4.6

Answer key

  1. 40
  2. 65
  3. 43
  4. 19
  5. 6.2
  6. 70
  7. 86
  8. 18
  9. 9.6
  10. 4.9
  11. 7.1
  12. 85
  13. 33
  14. 86
  15. 70
  16. 9.8
  17. 7.8
  18. 9.1
  19. 6.1
  20. 53
  21. 78
  22. 7.7
  23. 23
  24. 21
  25. 8.1
  26. 8.6
  27. 9.7
  28. 16
  29. 58
  30. 8.9
  31. 65
  32. 37
  33. 8.4
  34. 22
  35. 8.9
  36. 14
  37. 86
  38. 98
  39. 66
  40. 4.6

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