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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 277 · 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.√55 to 1 decimal place? (a) 7.4 (b) 7.2 (c) 7.3 (d) 7.5
  2. 2.√90 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.4 (d) 9.7
  3. 3.√70 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.3 (d) 8.2
  4. 4.√96 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.9 (d) 9.6
  5. 5.Best estimate of 2562 ÷ 66? (a) 37 (b) 3700 (c) 370
  6. 6.Best estimate of 993 ÷ 51? (a) 2000 (b) 20 (c) 200
  7. 7.Best estimate of 1203 ÷ 38? (a) 300 (b) 3000 (c) 30
  8. 8.Best estimate of 2163 ÷ 71? (a) 3100 (b) 310 (c) 31
  9. 9.Best estimate of 631 ÷ 26? (a) 2100 (b) 210 (c) 21
  10. 10.√50 to 1 decimal place? (a) 6.8 (b) 7.1 (c) 7.0 (d) 6.9
  11. 11.√74 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 8.6 (d) 8.7
  12. 12.Best estimate of 6203 ÷ 67? (a) 89 (b) 890 (c) 8900
  13. 13.Best estimate of 1952 ÷ 29? (a) 650 (b) 65 (c) 6500
  14. 14.Best estimate of 1617 ÷ 78? (a) 200 (b) 2000 (c) 20
  15. 15.Best estimate of 2379 ÷ 32? (a) 790 (b) 79 (c) 7900
  16. 16.Best estimate of 6398 ÷ 67? (a) 91 (b) 910 (c) 9100
  17. 17.Best estimate of 1428 ÷ 21? (a) 7100 (b) 71 (c) 710
  18. 18.√34 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.8 (d) 5.9
  19. 19.Best estimate of 1033 ÷ 21? (a) 520 (b) 52 (c) 5200
  20. 20.Best estimate of 6191 ÷ 69? (a) 88 (b) 8800 (c) 880
  21. 21.Best estimate of 2051 ÷ 24? (a) 1030 (b) 103 (c) 10300
  22. 22.Best estimate of 2044 ÷ 62? (a) 340 (b) 3400 (c) 34
  23. 23.Best estimate of 2146 ÷ 66? (a) 3100 (b) 310 (c) 31
  24. 24.√52 to 1 decimal place? (a) 6.9 (b) 7.1 (c) 7.0 (d) 7.2
  25. 25.√24 to 1 decimal place? (a) 4.9 (b) 5.0 (c) 5.1 (d) 4.8
  26. 26.Best estimate of 6192 ÷ 86? (a) 69 (b) 690 (c) 6900
  27. 27.Best estimate of 1391 ÷ 47? (a) 2800 (b) 28 (c) 280
  28. 28.Best estimate of 3496 ÷ 42? (a) 870 (b) 8700 (c) 87
  29. 29.√29 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.5 (d) 5.4
  30. 30.√56 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.6 (d) 7.7
  31. 31.Best estimate of 2701 ÷ 42? (a) 68 (b) 680 (c) 6800
  32. 32.Best estimate of 1192 ÷ 38? (a) 30 (b) 300 (c) 3000
  33. 33.Best estimate of 5356 ÷ 86? (a) 60 (b) 6000 (c) 600
  34. 34.√94 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 9.7 (d) 9.6
  35. 35.√66 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 8.0 (d) 7.9
  36. 36.√48 to 1 decimal place? (a) 7.0 (b) 7.1 (c) 6.9 (d) 6.8
  37. 37.√20 to 1 decimal place? (a) 4.5 (b) 4.8 (c) 4.6 (d) 4.7
  38. 38.Best estimate of 3395 ÷ 52? (a) 68 (b) 6800 (c) 680
  39. 39.Best estimate of 1154 ÷ 54? (a) 23 (b) 2300 (c) 230
  40. 40.√28 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.1 (d) 5.2

Answer key

  1. 7.4
  2. 9.5
  3. 8.4
  4. 9.8
  5. 37
  6. 20
  7. 30
  8. 31
  9. 21
  10. 7.1
  11. 8.6
  12. 89
  13. 65
  14. 20
  15. 79
  16. 91
  17. 71
  18. 5.8
  19. 52
  20. 88
  21. 103
  22. 34
  23. 31
  24. 7.2
  25. 4.9
  26. 69
  27. 28
  28. 87
  29. 5.4
  30. 7.5
  31. 68
  32. 30
  33. 60
  34. 9.7
  35. 8.1
  36. 6.9
  37. 4.5
  38. 68
  39. 23
  40. 5.3

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