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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 984 · 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.√29 to 1 decimal place? (a) 5.4 (b) 5.2 (c) 5.1 (d) 5.3
  2. 2.Best estimate of 5990 ÷ 86? (a) 6700 (b) 67 (c) 670
  3. 3.√65 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 7.9 (d) 8.2
  4. 4.Best estimate of 1573 ÷ 63? (a) 26 (b) 2600 (c) 260
  5. 5.Best estimate of 3268 ÷ 62? (a) 5400 (b) 54 (c) 540
  6. 6.√58 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.3 (d) 7.6
  7. 7.√23 to 1 decimal place? (a) 4.8 (b) 4.9 (c) 5.0 (d) 4.7
  8. 8.Best estimate of 5595 ÷ 84? (a) 700 (b) 7000 (c) 70
  9. 9.Best estimate of 6087 ÷ 86? (a) 680 (b) 6800 (c) 68
  10. 10.√34 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.5 (d) 5.8
  11. 11.Best estimate of 3523 ÷ 57? (a) 5900 (b) 590 (c) 59
  12. 12.Best estimate of 3521 ÷ 56? (a) 5900 (b) 59 (c) 590
  13. 13.√61 to 1 decimal place? (a) 7.7 (b) 7.9 (c) 7.8 (d) 7.6
  14. 14.Best estimate of 3528 ÷ 46? (a) 7100 (b) 71 (c) 710
  15. 15.√30 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.6 (d) 5.5
  16. 16.√94 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 9.6 (d) 9.7
  17. 17.Best estimate of 1637 ÷ 49? (a) 33 (b) 3300 (c) 330
  18. 18.√59 to 1 decimal place? (a) 8.0 (b) 7.8 (c) 7.7 (d) 7.9
  19. 19.Best estimate of 2833 ÷ 32? (a) 940 (b) 9400 (c) 94
  20. 20.Best estimate of 4668 ÷ 54? (a) 930 (b) 93 (c) 9300
  21. 21.Best estimate of 2784 ÷ 42? (a) 700 (b) 7000 (c) 70
  22. 22.Best estimate of 2199 ÷ 39? (a) 5500 (b) 550 (c) 55
  23. 23.√55 to 1 decimal place? (a) 7.5 (b) 7.3 (c) 7.4 (d) 7.2
  24. 24.√71 to 1 decimal place? (a) 8.5 (b) 8.2 (c) 8.3 (d) 8.4
  25. 25.√77 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 8.9 (d) 9.1
  26. 26.√37 to 1 decimal place? (a) 6.2 (b) 6.4 (c) 6.3 (d) 6.1
  27. 27.√41 to 1 decimal place? (a) 6.3 (b) 6.5 (c) 6.4 (d) 6.2
  28. 28.√74 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.5 (d) 8.4
  29. 29.Best estimate of 686 ÷ 27? (a) 2300 (b) 230 (c) 23
  30. 30.√69 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.5 (d) 8.6
  31. 31.√92 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.9 (d) 9.6
  32. 32.Best estimate of 1259 ÷ 33? (a) 4200 (b) 42 (c) 420
  33. 33.Best estimate of 811 ÷ 36? (a) 20 (b) 2000 (c) 200
  34. 34.√67 to 1 decimal place? (a) 8.3 (b) 8.1 (c) 8.4 (d) 8.2
  35. 35.Best estimate of 2803 ÷ 46? (a) 56 (b) 560 (c) 5600
  36. 36.√42 to 1 decimal place? (a) 6.6 (b) 6.5 (c) 6.7 (d) 6.4
  37. 37.√22 to 1 decimal place? (a) 4.7 (b) 4.4 (c) 4.6 (d) 4.5
  38. 38.√86 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 9.2 (d) 9.3
  39. 39.Best estimate of 860 ÷ 36? (a) 220 (b) 2200 (c) 22
  40. 40.Best estimate of 1650 ÷ 29? (a) 5500 (b) 550 (c) 55

Answer key

  1. 5.4
  2. 67
  3. 8.1
  4. 26
  5. 54
  6. 7.6
  7. 4.8
  8. 70
  9. 68
  10. 5.8
  11. 59
  12. 59
  13. 7.8
  14. 71
  15. 5.5
  16. 9.7
  17. 33
  18. 7.7
  19. 94
  20. 93
  21. 70
  22. 55
  23. 7.4
  24. 8.4
  25. 8.8
  26. 6.1
  27. 6.4
  28. 8.6
  29. 23
  30. 8.3
  31. 9.6
  32. 42
  33. 20
  34. 8.2
  35. 56
  36. 6.5
  37. 4.7
  38. 9.3
  39. 22
  40. 55

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