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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 612 · 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 1255 ÷ 56? (a) 210 (b) 2100 (c) 21
  2. 2.Best estimate of 3358 ÷ 39? (a) 84 (b) 840 (c) 8400
  3. 3.Best estimate of 6319 ÷ 82? (a) 79 (b) 7900 (c) 790
  4. 4.√29 to 1 decimal place? (a) 5.1 (b) 5.3 (c) 5.4 (d) 5.2
  5. 5.√92 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.5 (d) 9.6
  6. 6.Best estimate of 679 ÷ 21? (a) 34 (b) 3400 (c) 340
  7. 7.√82 to 1 decimal place? (a) 9.2 (b) 9.0 (c) 9.1 (d) 9.3
  8. 8.Best estimate of 1582 ÷ 87? (a) 1800 (b) 180 (c) 18
  9. 9.√59 to 1 decimal place? (a) 7.9 (b) 7.6 (c) 7.7 (d) 7.8
  10. 10.Best estimate of 4433 ÷ 48? (a) 8900 (b) 890 (c) 89
  11. 11.Best estimate of 2264 ÷ 49? (a) 450 (b) 4500 (c) 45
  12. 12.Best estimate of 5069 ÷ 64? (a) 84 (b) 8400 (c) 840
  13. 13.√94 to 1 decimal place? (a) 9.9 (b) 10.0 (c) 9.8 (d) 9.7
  14. 14.√21 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 4.5 (d) 4.6
  15. 15.√45 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.5 (d) 6.8
  16. 16.√77 to 1 decimal place? (a) 8.9 (b) 8.6 (c) 8.8 (d) 8.7
  17. 17.Best estimate of 1023 ÷ 52? (a) 200 (b) 20 (c) 2000
  18. 18.√24 to 1 decimal place? (a) 4.8 (b) 5.0 (c) 4.9 (d) 5.1
  19. 19.√90 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.6 (d) 9.5
  20. 20.Best estimate of 3779 ÷ 46? (a) 7600 (b) 76 (c) 760
  21. 21.√84 to 1 decimal place? (a) 9.0 (b) 9.2 (c) 9.3 (d) 9.1
  22. 22.Best estimate of 1402 ÷ 27? (a) 47 (b) 4700 (c) 470
  23. 23.Best estimate of 988 ÷ 22? (a) 4900 (b) 490 (c) 49
  24. 24.√55 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.3 (d) 7.5
  25. 25.√34 to 1 decimal place? (a) 5.8 (b) 5.6 (c) 5.7 (d) 5.5
  26. 26.√87 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.3 (d) 9.0
  27. 27.Best estimate of 2496 ÷ 32? (a) 8300 (b) 830 (c) 83
  28. 28.Best estimate of 628 ÷ 32? (a) 210 (b) 21 (c) 2100
  29. 29.√75 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 9.0 (d) 8.7
  30. 30.√47 to 1 decimal place? (a) 6.7 (b) 7.0 (c) 6.8 (d) 6.9
  31. 31.Best estimate of 4210 ÷ 57? (a) 70 (b) 7000 (c) 700
  32. 32.√23 to 1 decimal place? (a) 4.9 (b) 4.8 (c) 5.1 (d) 5.0
  33. 33.Best estimate of 2470 ÷ 59? (a) 4100 (b) 410 (c) 41
  34. 34.√74 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.3 (d) 8.6
  35. 35.Best estimate of 673 ÷ 48? (a) 1300 (b) 13 (c) 130
  36. 36.Best estimate of 2536 ÷ 71? (a) 36 (b) 360 (c) 3600
  37. 37.Best estimate of 3341 ÷ 89? (a) 37 (b) 370 (c) 3700
  38. 38.Best estimate of 4216 ÷ 54? (a) 84 (b) 840 (c) 8400
  39. 39.√72 to 1 decimal place? (a) 8.7 (b) 8.5 (c) 8.4 (d) 8.6
  40. 40.√88 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.5 (d) 9.4

Answer key

  1. 21
  2. 84
  3. 79
  4. 5.4
  5. 9.6
  6. 34
  7. 9.1
  8. 18
  9. 7.7
  10. 89
  11. 45
  12. 84
  13. 9.7
  14. 4.6
  15. 6.7
  16. 8.8
  17. 20
  18. 4.9
  19. 9.5
  20. 76
  21. 9.2
  22. 47
  23. 49
  24. 7.4
  25. 5.8
  26. 9.3
  27. 83
  28. 21
  29. 8.7
  30. 6.9
  31. 70
  32. 4.8
  33. 41
  34. 8.6
  35. 13
  36. 36
  37. 37
  38. 84
  39. 8.5
  40. 9.4

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