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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 327 · 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 2724 ÷ 36? (a) 6800 (b) 680 (c) 68
  2. 2.Best estimate of 2136 ÷ 36? (a) 530 (b) 53 (c) 5300
  3. 3.Best estimate of 3452 ÷ 56? (a) 580 (b) 5800 (c) 58
  4. 4.√88 to 1 decimal place? (a) 9.1 (b) 9.4 (c) 9.3 (d) 9.2
  5. 5.√50 to 1 decimal place? (a) 7.1 (b) 7.3 (c) 7.4 (d) 7.2
  6. 6.√58 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.8 (d) 7.9
  7. 7.√20 to 1 decimal place? (a) 4.7 (b) 4.6 (c) 4.8 (d) 4.5
  8. 8.√48 to 1 decimal place? (a) 6.8 (b) 6.7 (c) 6.9 (d) 6.6
  9. 9.√87 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.2 (d) 9.5
  10. 10.√77 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 8.9 (d) 8.8
  11. 11.√61 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.6 (d) 7.5
  12. 12.√26 to 1 decimal place? (a) 5.2 (b) 5.1 (c) 5.3 (d) 5.0
  13. 13.Best estimate of 2848 ÷ 36? (a) 7100 (b) 710 (c) 71
  14. 14.Best estimate of 3424 ÷ 64? (a) 57 (b) 5700 (c) 570
  15. 15.√90 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.7 (d) 9.8
  16. 16.√53 to 1 decimal place? (a) 7.1 (b) 7.0 (c) 7.3 (d) 7.2
  17. 17.Best estimate of 1249 ÷ 33? (a) 4200 (b) 42 (c) 420
  18. 18.Best estimate of 1569 ÷ 53? (a) 3100 (b) 310 (c) 31
  19. 19.Best estimate of 2543 ÷ 31? (a) 85 (b) 8500 (c) 850
  20. 20.Best estimate of 1920 ÷ 24? (a) 9600 (b) 96 (c) 960
  21. 21.Best estimate of 4800 ÷ 64? (a) 8000 (b) 80 (c) 800
  22. 22.√55 to 1 decimal place? (a) 7.1 (b) 7.3 (c) 7.2 (d) 7.4
  23. 23.√79 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 9.1 (d) 9.0
  24. 24.Best estimate of 1148 ÷ 41? (a) 290 (b) 29 (c) 2900
  25. 25.√34 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.5 (d) 5.8
  26. 26.√96 to 1 decimal place? (a) 10.1 (b) 9.9 (c) 10.0 (d) 9.8
  27. 27.√82 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.4 (d) 9.3
  28. 28.Best estimate of 6917 ÷ 73? (a) 99 (b) 9900 (c) 990
  29. 29.Best estimate of 920 ÷ 47? (a) 1800 (b) 18 (c) 180
  30. 30.√30 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.5 (d) 5.2
  31. 31.√31 to 1 decimal place? (a) 5.6 (b) 5.8 (c) 5.5 (d) 5.7
  32. 32.√37 to 1 decimal place? (a) 6.0 (b) 6.2 (c) 6.3 (d) 6.1
  33. 33.√89 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.5 (d) 9.3
  34. 34.Best estimate of 1338 ÷ 42? (a) 3300 (b) 33 (c) 330
  35. 35.Best estimate of 1918 ÷ 58? (a) 320 (b) 3200 (c) 32
  36. 36.Best estimate of 362 ÷ 24? (a) 1800 (b) 18 (c) 180
  37. 37.Best estimate of 4147 ÷ 67? (a) 590 (b) 5900 (c) 59
  38. 38.Best estimate of 3101 ÷ 66? (a) 440 (b) 4400 (c) 44
  39. 39.Best estimate of 3090 ÷ 74? (a) 4400 (b) 44 (c) 440
  40. 40.Best estimate of 3404 ÷ 46? (a) 680 (b) 68 (c) 6800

Answer key

  1. 68
  2. 53
  3. 58
  4. 9.4
  5. 7.1
  6. 7.6
  7. 4.5
  8. 6.9
  9. 9.3
  10. 8.8
  11. 7.8
  12. 5.1
  13. 71
  14. 57
  15. 9.5
  16. 7.3
  17. 42
  18. 31
  19. 85
  20. 96
  21. 80
  22. 7.4
  23. 8.9
  24. 29
  25. 5.8
  26. 9.8
  27. 9.1
  28. 99
  29. 18
  30. 5.5
  31. 5.6
  32. 6.1
  33. 9.4
  34. 33
  35. 32
  36. 18
  37. 59
  38. 44
  39. 44
  40. 68

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