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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 673 · 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 2074 ÷ 26? (a) 690 (b) 6900 (c) 69
  2. 2.Best estimate of 301 ÷ 24? (a) 1500 (b) 15 (c) 150
  3. 3.Best estimate of 1806 ÷ 27? (a) 6000 (b) 60 (c) 600
  4. 4.Best estimate of 2887 ÷ 33? (a) 9600 (b) 960 (c) 96
  5. 5.√62 to 1 decimal place? (a) 7.9 (b) 7.6 (c) 7.8 (d) 7.7
  6. 6.√58 to 1 decimal place? (a) 7.8 (b) 7.5 (c) 7.6 (d) 7.7
  7. 7.√48 to 1 decimal place? (a) 7.0 (b) 6.9 (c) 7.1 (d) 7.2
  8. 8.Best estimate of 470 ÷ 31? (a) 16 (b) 160 (c) 1600
  9. 9.√38 to 1 decimal place? (a) 6.2 (b) 6.4 (c) 6.5 (d) 6.3
  10. 10.√69 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.4 (d) 8.1
  11. 11.Best estimate of 1734 ÷ 36? (a) 4300 (b) 430 (c) 43
  12. 12.Best estimate of 1217 ÷ 36? (a) 300 (b) 3000 (c) 30
  13. 13.√20 to 1 decimal place? (a) 4.6 (b) 4.5 (c) 4.7 (d) 4.4
  14. 14.Best estimate of 1469 ÷ 86? (a) 16 (b) 160 (c) 1600
  15. 15.Best estimate of 1678 ÷ 79? (a) 21 (b) 2100 (c) 210
  16. 16.√63 to 1 decimal place? (a) 8.1 (b) 7.8 (c) 7.9 (d) 8.0
  17. 17.Best estimate of 890 ÷ 36? (a) 22 (b) 2200 (c) 220
  18. 18.√34 to 1 decimal place? (a) 5.6 (b) 5.8 (c) 5.7 (d) 5.5
  19. 19.√89 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.5 (d) 9.2
  20. 20.Best estimate of 1615 ÷ 42? (a) 400 (b) 40 (c) 4000
  21. 21.√66 to 1 decimal place? (a) 8.0 (b) 8.2 (c) 8.3 (d) 8.1
  22. 22.√26 to 1 decimal place? (a) 5.1 (b) 4.9 (c) 5.2 (d) 5.0
  23. 23.Best estimate of 547 ÷ 26? (a) 18 (b) 1800 (c) 180
  24. 24.√37 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 5.9 (d) 6.0
  25. 25.Best estimate of 1699 ÷ 82? (a) 2100 (b) 210 (c) 21
  26. 26.√45 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.8 (d) 6.5
  27. 27.Best estimate of 5774 ÷ 72? (a) 8200 (b) 820 (c) 82
  28. 28.√35 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 6.2 (d) 6.1
  29. 29.Best estimate of 1770 ÷ 86? (a) 200 (b) 20 (c) 2000
  30. 30.Best estimate of 2361 ÷ 43? (a) 59 (b) 590 (c) 5900
  31. 31.√40 to 1 decimal place? (a) 6.3 (b) 6.0 (c) 6.2 (d) 6.1
  32. 32.Best estimate of 2388 ÷ 63? (a) 4000 (b) 40 (c) 400
  33. 33.√71 to 1 decimal place? (a) 8.7 (b) 8.5 (c) 8.6 (d) 8.4
  34. 34.Best estimate of 1288 ÷ 87? (a) 1400 (b) 14 (c) 140
  35. 35.Best estimate of 5220 ÷ 61? (a) 870 (b) 87 (c) 8700
  36. 36.Best estimate of 999 ÷ 31? (a) 330 (b) 33 (c) 3300
  37. 37.Best estimate of 3287 ÷ 53? (a) 660 (b) 66 (c) 6600
  38. 38.√41 to 1 decimal place? (a) 6.5 (b) 6.7 (c) 6.6 (d) 6.4
  39. 39.Best estimate of 4628 ÷ 66? (a) 6600 (b) 660 (c) 66
  40. 40.Best estimate of 707 ÷ 23? (a) 3500 (b) 35 (c) 350

Answer key

  1. 69
  2. 15
  3. 60
  4. 96
  5. 7.9
  6. 7.6
  7. 6.9
  8. 16
  9. 6.2
  10. 8.3
  11. 43
  12. 30
  13. 4.5
  14. 16
  15. 21
  16. 7.9
  17. 22
  18. 5.8
  19. 9.4
  20. 40
  21. 8.1
  22. 5.1
  23. 18
  24. 6.1
  25. 21
  26. 6.7
  27. 82
  28. 5.9
  29. 20
  30. 59
  31. 6.3
  32. 40
  33. 8.4
  34. 14
  35. 87
  36. 33
  37. 66
  38. 6.4
  39. 66
  40. 35

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