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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 957 · 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 4280 ÷ 64? (a) 710 (b) 7100 (c) 71
  2. 2.Best estimate of 3608 ÷ 48? (a) 7200 (b) 72 (c) 720
  3. 3.√37 to 1 decimal place? (a) 6.1 (b) 5.9 (c) 6.0 (d) 6.2
  4. 4.Best estimate of 1583 ÷ 68? (a) 23 (b) 2300 (c) 230
  5. 5.√88 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.3 (d) 9.4
  6. 6.Best estimate of 6252 ÷ 67? (a) 8900 (b) 89 (c) 890
  7. 7.Best estimate of 3778 ÷ 56? (a) 6300 (b) 63 (c) 630
  8. 8.Best estimate of 4691 ÷ 82? (a) 590 (b) 59 (c) 5900
  9. 9.Best estimate of 5510 ÷ 71? (a) 790 (b) 79 (c) 7900
  10. 10.Best estimate of 3358 ÷ 38? (a) 84 (b) 840 (c) 8400
  11. 11.Best estimate of 1027 ÷ 38? (a) 26 (b) 260 (c) 2600
  12. 12.√71 to 1 decimal place? (a) 8.2 (b) 8.4 (c) 8.3 (d) 8.5
  13. 13.Best estimate of 3765 ÷ 57? (a) 630 (b) 6300 (c) 63
  14. 14.Best estimate of 992 ÷ 54? (a) 2000 (b) 200 (c) 20
  15. 15.√98 to 1 decimal place? (a) 10.1 (b) 10.0 (c) 9.9 (d) 10.2
  16. 16.√35 to 1 decimal place? (a) 5.6 (b) 5.8 (c) 5.7 (d) 5.9
  17. 17.√92 to 1 decimal place? (a) 9.7 (b) 9.5 (c) 9.6 (d) 9.8
  18. 18.√34 to 1 decimal place? (a) 5.9 (b) 5.8 (c) 5.6 (d) 5.7
  19. 19.Best estimate of 879 ÷ 64? (a) 15 (b) 1500 (c) 150
  20. 20.Best estimate of 2063 ÷ 42? (a) 52 (b) 5200 (c) 520
  21. 21.√20 to 1 decimal place? (a) 4.6 (b) 4.5 (c) 4.4 (d) 4.3
  22. 22.Best estimate of 584 ÷ 47? (a) 1200 (b) 120 (c) 12
  23. 23.√58 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.7 (d) 7.6
  24. 24.Best estimate of 4435 ÷ 48? (a) 890 (b) 89 (c) 8900
  25. 25.Best estimate of 1927 ÷ 37? (a) 4800 (b) 48 (c) 480
  26. 26.Best estimate of 2066 ÷ 23? (a) 103 (b) 1030 (c) 10300
  27. 27.Best estimate of 2079 ÷ 24? (a) 1040 (b) 10400 (c) 104
  28. 28.√28 to 1 decimal place? (a) 5.3 (b) 5.2 (c) 5.5 (d) 5.4
  29. 29.√32 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.8 (d) 5.7
  30. 30.Best estimate of 2873 ÷ 42? (a) 7200 (b) 72 (c) 720
  31. 31.√29 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.5 (d) 5.4
  32. 32.Best estimate of 6662 ÷ 83? (a) 83 (b) 830 (c) 8300
  33. 33.Best estimate of 716 ÷ 38? (a) 1800 (b) 18 (c) 180
  34. 34.√78 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 8.9 (d) 8.8
  35. 35.Best estimate of 2043 ÷ 28? (a) 680 (b) 6800 (c) 68
  36. 36.√42 to 1 decimal place? (a) 6.8 (b) 6.7 (c) 6.6 (d) 6.5
  37. 37.Best estimate of 954 ÷ 67? (a) 1400 (b) 140 (c) 14
  38. 38.Best estimate of 5430 ÷ 66? (a) 78 (b) 780 (c) 7800
  39. 39.√22 to 1 decimal place? (a) 4.7 (b) 4.8 (c) 4.9 (d) 4.6
  40. 40.Best estimate of 1339 ÷ 87? (a) 1500 (b) 150 (c) 15

Answer key

  1. 71
  2. 72
  3. 6.1
  4. 23
  5. 9.4
  6. 89
  7. 63
  8. 59
  9. 79
  10. 84
  11. 26
  12. 8.4
  13. 63
  14. 20
  15. 9.9
  16. 5.9
  17. 9.6
  18. 5.8
  19. 15
  20. 52
  21. 4.5
  22. 12
  23. 7.6
  24. 89
  25. 48
  26. 103
  27. 104
  28. 5.3
  29. 5.7
  30. 72
  31. 5.4
  32. 83
  33. 18
  34. 8.8
  35. 68
  36. 6.5
  37. 14
  38. 78
  39. 4.7
  40. 15

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