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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 528 · 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 3918 ÷ 64? (a) 650 (b) 65 (c) 6500
  2. 2.Best estimate of 2917 ÷ 84? (a) 3600 (b) 360 (c) 36
  3. 3.√22 to 1 decimal place? (a) 4.9 (b) 4.7 (c) 4.6 (d) 4.8
  4. 4.Best estimate of 1768 ÷ 57? (a) 290 (b) 29 (c) 2900
  5. 5.√52 to 1 decimal place? (a) 7.1 (b) 7.3 (c) 7.0 (d) 7.2
  6. 6.√28 to 1 decimal place? (a) 5.3 (b) 5.5 (c) 5.4 (d) 5.2
  7. 7.√75 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 8.7 (d) 9.0
  8. 8.Best estimate of 5605 ÷ 81? (a) 7000 (b) 70 (c) 700
  9. 9.√56 to 1 decimal place? (a) 7.3 (b) 7.5 (c) 7.2 (d) 7.4
  10. 10.√82 to 1 decimal place? (a) 9.0 (b) 9.3 (c) 9.2 (d) 9.1
  11. 11.Best estimate of 1091 ÷ 31? (a) 36 (b) 360 (c) 3600
  12. 12.Best estimate of 1135 ÷ 26? (a) 3800 (b) 38 (c) 380
  13. 13.Best estimate of 5350 ÷ 76? (a) 670 (b) 6700 (c) 67
  14. 14.√94 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.9 (d) 9.6
  15. 15.Best estimate of 1900 ÷ 86? (a) 21 (b) 2100 (c) 210
  16. 16.Best estimate of 1993 ÷ 22? (a) 100 (b) 10000 (c) 1000
  17. 17.Best estimate of 1966 ÷ 67? (a) 2800 (b) 280 (c) 28
  18. 18.√20 to 1 decimal place? (a) 4.5 (b) 4.6 (c) 4.7 (d) 4.8
  19. 19.Best estimate of 1406 ÷ 21? (a) 7000 (b) 700 (c) 70
  20. 20.√29 to 1 decimal place? (a) 5.7 (b) 5.5 (c) 5.4 (d) 5.6
  21. 21.Best estimate of 1694 ÷ 52? (a) 340 (b) 34 (c) 3400
  22. 22.Best estimate of 1504 ÷ 26? (a) 5000 (b) 500 (c) 50
  23. 23.√42 to 1 decimal place? (a) 6.5 (b) 6.4 (c) 6.2 (d) 6.3
  24. 24.Best estimate of 1137 ÷ 47? (a) 230 (b) 2300 (c) 23
  25. 25.Best estimate of 6755 ÷ 86? (a) 7500 (b) 750 (c) 75
  26. 26.Best estimate of 1665 ÷ 26? (a) 560 (b) 5600 (c) 56
  27. 27.Best estimate of 1501 ÷ 33? (a) 50 (b) 5000 (c) 500
  28. 28.√37 to 1 decimal place? (a) 6.1 (b) 5.9 (c) 6.0 (d) 5.8
  29. 29.√43 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.8 (d) 6.5
  30. 30.Best estimate of 1420 ÷ 52? (a) 2800 (b) 280 (c) 28
  31. 31.Best estimate of 2488 ÷ 36? (a) 62 (b) 6200 (c) 620
  32. 32.Best estimate of 3469 ÷ 68? (a) 50 (b) 5000 (c) 500
  33. 33.Best estimate of 1492 ÷ 26? (a) 500 (b) 5000 (c) 50
  34. 34.√92 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.4 (d) 9.3
  35. 35.Best estimate of 515 ÷ 21? (a) 260 (b) 2600 (c) 26
  36. 36.√26 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 5.1 (d) 4.8
  37. 37.Best estimate of 2660 ÷ 73? (a) 38 (b) 3800 (c) 380
  38. 38.Best estimate of 5422 ÷ 63? (a) 90 (b) 900 (c) 9000
  39. 39.√47 to 1 decimal place? (a) 6.7 (b) 7.0 (c) 6.9 (d) 6.8
  40. 40.Best estimate of 2501 ÷ 37? (a) 630 (b) 63 (c) 6300

Answer key

  1. 65
  2. 36
  3. 4.7
  4. 29
  5. 7.2
  6. 5.3
  7. 8.7
  8. 70
  9. 7.5
  10. 9.1
  11. 36
  12. 38
  13. 67
  14. 9.7
  15. 21
  16. 100
  17. 28
  18. 4.5
  19. 70
  20. 5.4
  21. 34
  22. 50
  23. 6.5
  24. 23
  25. 75
  26. 56
  27. 50
  28. 6.1
  29. 6.6
  30. 28
  31. 62
  32. 50
  33. 50
  34. 9.6
  35. 26
  36. 5.1
  37. 38
  38. 90
  39. 6.9
  40. 63

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