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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 869 · 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 2844 ÷ 37? (a) 71 (b) 7100 (c) 710
  2. 2.√88 to 1 decimal place? (a) 9.3 (b) 9.5 (c) 9.4 (d) 9.6
  3. 3.Best estimate of 4148 ÷ 82? (a) 5200 (b) 52 (c) 520
  4. 4.Best estimate of 6478 ÷ 72? (a) 93 (b) 930 (c) 9300
  5. 5.Best estimate of 648 ÷ 47? (a) 130 (b) 1300 (c) 13
  6. 6.√29 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.5 (d) 5.4
  7. 7.Best estimate of 3857 ÷ 82? (a) 4800 (b) 480 (c) 48
  8. 8.√52 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.4 (d) 7.1
  9. 9.√37 to 1 decimal place? (a) 6.2 (b) 6.4 (c) 6.1 (d) 6.3
  10. 10.Best estimate of 1704 ÷ 27? (a) 570 (b) 5700 (c) 57
  11. 11.√84 to 1 decimal place? (a) 9.4 (b) 9.2 (c) 9.3 (d) 9.5
  12. 12.Best estimate of 6496 ÷ 72? (a) 9300 (b) 93 (c) 930
  13. 13.√94 to 1 decimal place? (a) 9.4 (b) 9.7 (c) 9.5 (d) 9.6
  14. 14.Best estimate of 3665 ÷ 42? (a) 92 (b) 920 (c) 9200
  15. 15.Best estimate of 3627 ÷ 38? (a) 9100 (b) 91 (c) 910
  16. 16.Best estimate of 754 ÷ 21? (a) 380 (b) 38 (c) 3800
  17. 17.Best estimate of 4880 ÷ 51? (a) 9800 (b) 980 (c) 98
  18. 18.Best estimate of 1428 ÷ 28? (a) 480 (b) 48 (c) 4800
  19. 19.Best estimate of 4003 ÷ 42? (a) 1000 (b) 10000 (c) 100
  20. 20.Best estimate of 6970 ÷ 73? (a) 1000 (b) 100 (c) 10000
  21. 21.√78 to 1 decimal place? (a) 9.1 (b) 8.9 (c) 9.0 (d) 8.8
  22. 22.Best estimate of 4519 ÷ 52? (a) 9000 (b) 90 (c) 900
  23. 23.Best estimate of 1948 ÷ 26? (a) 6500 (b) 650 (c) 65
  24. 24.Best estimate of 2191 ÷ 66? (a) 31 (b) 3100 (c) 310
  25. 25.Best estimate of 4035 ÷ 43? (a) 1010 (b) 101 (c) 10100
  26. 26.√22 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 4.7 (d) 4.8
  27. 27.Best estimate of 1120 ÷ 41? (a) 280 (b) 2800 (c) 28
  28. 28.√80 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 8.6 (d) 8.7
  29. 29.Best estimate of 4029 ÷ 83? (a) 50 (b) 5000 (c) 500
  30. 30.√45 to 1 decimal place? (a) 6.9 (b) 6.7 (c) 7.0 (d) 6.8
  31. 31.√98 to 1 decimal place? (a) 10.0 (b) 9.9 (c) 9.7 (d) 9.8
  32. 32.Best estimate of 774 ÷ 24? (a) 3900 (b) 390 (c) 39
  33. 33.√83 to 1 decimal place? (a) 8.8 (b) 9.1 (c) 8.9 (d) 9.0
  34. 34.√44 to 1 decimal place? (a) 6.7 (b) 6.6 (c) 6.8 (d) 6.9
  35. 35.Best estimate of 978 ÷ 56? (a) 1600 (b) 16 (c) 160
  36. 36.√42 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.4 (d) 6.3
  37. 37.√59 to 1 decimal place? (a) 7.7 (b) 8.0 (c) 7.9 (d) 7.8
  38. 38.√38 to 1 decimal place? (a) 6.3 (b) 6.2 (c) 6.0 (d) 6.1
  39. 39.√96 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 9.7 (d) 9.6
  40. 40.Best estimate of 1481 ÷ 28? (a) 490 (b) 4900 (c) 49

Answer key

  1. 71
  2. 9.4
  3. 52
  4. 93
  5. 13
  6. 5.4
  7. 48
  8. 7.2
  9. 6.1
  10. 57
  11. 9.2
  12. 93
  13. 9.7
  14. 92
  15. 91
  16. 38
  17. 98
  18. 48
  19. 100
  20. 100
  21. 8.8
  22. 90
  23. 65
  24. 31
  25. 101
  26. 4.7
  27. 28
  28. 8.9
  29. 50
  30. 6.7
  31. 9.9
  32. 39
  33. 9.1
  34. 6.6
  35. 16
  36. 6.5
  37. 7.7
  38. 6.2
  39. 9.8
  40. 49

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