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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 978 · 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.√40 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.2 (d) 6.5
  2. 2.√69 to 1 decimal place? (a) 8.0 (b) 8.2 (c) 8.1 (d) 8.3
  3. 3.√48 to 1 decimal place? (a) 6.9 (b) 6.7 (c) 7.0 (d) 6.8
  4. 4.√44 to 1 decimal place? (a) 6.5 (b) 6.7 (c) 6.6 (d) 6.8
  5. 5.√98 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 10.1 (d) 10.0
  6. 6.Best estimate of 2407 ÷ 66? (a) 3400 (b) 340 (c) 34
  7. 7.√29 to 1 decimal place? (a) 5.4 (b) 5.2 (c) 5.3 (d) 5.5
  8. 8.√63 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 7.7 (d) 7.6
  9. 9.√24 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.9 (d) 4.8
  10. 10.Best estimate of 1863 ÷ 58? (a) 3100 (b) 31 (c) 310
  11. 11.√94 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.6 (d) 9.9
  12. 12.Best estimate of 6036 ÷ 69? (a) 860 (b) 86 (c) 8600
  13. 13.√56 to 1 decimal place? (a) 7.4 (b) 7.7 (c) 7.6 (d) 7.5
  14. 14.√92 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.5 (d) 9.6
  15. 15.Best estimate of 2795 ÷ 42? (a) 7000 (b) 70 (c) 700
  16. 16.√28 to 1 decimal place? (a) 5.5 (b) 5.3 (c) 5.2 (d) 5.4
  17. 17.√62 to 1 decimal place? (a) 7.9 (b) 8.2 (c) 8.1 (d) 8.0
  18. 18.√96 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 10.0 (d) 9.9
  19. 19.Best estimate of 1311 ÷ 54? (a) 260 (b) 26 (c) 2600
  20. 20.Best estimate of 6475 ÷ 74? (a) 930 (b) 9300 (c) 93
  21. 21.Best estimate of 1859 ÷ 42? (a) 4600 (b) 460 (c) 46
  22. 22.Best estimate of 5735 ÷ 64? (a) 960 (b) 9600 (c) 96
  23. 23.√50 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.0 (d) 6.9
  24. 24.Best estimate of 3700 ÷ 73? (a) 530 (b) 53 (c) 5300
  25. 25.Best estimate of 1802 ÷ 36? (a) 4500 (b) 45 (c) 450
  26. 26.√23 to 1 decimal place? (a) 4.6 (b) 4.8 (c) 4.5 (d) 4.7
  27. 27.Best estimate of 2577 ÷ 78? (a) 320 (b) 3200 (c) 32
  28. 28.Best estimate of 4727 ÷ 88? (a) 53 (b) 530 (c) 5300
  29. 29.Best estimate of 3365 ÷ 69? (a) 480 (b) 4800 (c) 48
  30. 30.√65 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 8.1 (d) 8.2
  31. 31.Best estimate of 438 ÷ 21? (a) 22 (b) 2200 (c) 220
  32. 32.Best estimate of 4173 ÷ 79? (a) 52 (b) 520 (c) 5200
  33. 33.√38 to 1 decimal place? (a) 6.2 (b) 6.4 (c) 6.1 (d) 6.3
  34. 34.Best estimate of 3299 ÷ 46? (a) 66 (b) 6600 (c) 660
  35. 35.√55 to 1 decimal place? (a) 7.4 (b) 7.2 (c) 7.1 (d) 7.3
  36. 36.Best estimate of 1090 ÷ 84? (a) 14 (b) 140 (c) 1400
  37. 37.Best estimate of 1729 ÷ 51? (a) 350 (b) 3500 (c) 35
  38. 38.√37 to 1 decimal place? (a) 6.4 (b) 6.2 (c) 6.3 (d) 6.1
  39. 39.Best estimate of 2868 ÷ 61? (a) 480 (b) 4800 (c) 48
  40. 40.√34 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.9 (d) 5.8

Answer key

  1. 6.3
  2. 8.3
  3. 6.9
  4. 6.6
  5. 9.9
  6. 34
  7. 5.4
  8. 7.9
  9. 4.9
  10. 31
  11. 9.7
  12. 86
  13. 7.5
  14. 9.6
  15. 70
  16. 5.3
  17. 7.9
  18. 9.8
  19. 26
  20. 93
  21. 46
  22. 96
  23. 7.1
  24. 53
  25. 45
  26. 4.8
  27. 32
  28. 53
  29. 48
  30. 8.1
  31. 22
  32. 52
  33. 6.2
  34. 66
  35. 7.4
  36. 14
  37. 35
  38. 6.1
  39. 48
  40. 5.8

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