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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 798 · 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 775 ÷ 37? (a) 19 (b) 1900 (c) 190
  2. 2.√62 to 1 decimal place? (a) 7.9 (b) 8.1 (c) 7.8 (d) 8.0
  3. 3.Best estimate of 914 ÷ 31? (a) 300 (b) 3000 (c) 30
  4. 4.Best estimate of 4107 ÷ 51? (a) 8200 (b) 82 (c) 820
  5. 5.Best estimate of 2473 ÷ 72? (a) 35 (b) 3500 (c) 350
  6. 6.Best estimate of 817 ÷ 54? (a) 16 (b) 160 (c) 1600
  7. 7.Best estimate of 2075 ÷ 22? (a) 104 (b) 1040 (c) 10400
  8. 8.Best estimate of 4949 ÷ 84? (a) 6200 (b) 62 (c) 620
  9. 9.Best estimate of 1986 ÷ 33? (a) 6600 (b) 660 (c) 66
  10. 10.Best estimate of 1458 ÷ 32? (a) 49 (b) 490 (c) 4900
  11. 11.√82 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 8.9 (d) 9.1
  12. 12.√80 to 1 decimal place? (a) 8.9 (b) 8.7 (c) 9.0 (d) 8.8
  13. 13.Best estimate of 2041 ÷ 76? (a) 260 (b) 2600 (c) 26
  14. 14.Best estimate of 2596 ÷ 52? (a) 5200 (b) 520 (c) 52
  15. 15.Best estimate of 1971 ÷ 32? (a) 660 (b) 6600 (c) 66
  16. 16.√24 to 1 decimal place? (a) 4.6 (b) 4.8 (c) 4.7 (d) 4.9
  17. 17.√26 to 1 decimal place? (a) 4.9 (b) 5.1 (c) 5.2 (d) 5.0
  18. 18.Best estimate of 3586 ÷ 38? (a) 9000 (b) 90 (c) 900
  19. 19.√96 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 10.0 (d) 9.7
  20. 20.√37 to 1 decimal place? (a) 6.0 (b) 5.8 (c) 5.9 (d) 6.1
  21. 21.Best estimate of 5422 ÷ 62? (a) 90 (b) 9000 (c) 900
  22. 22.Best estimate of 674 ÷ 47? (a) 130 (b) 1300 (c) 13
  23. 23.Best estimate of 1985 ÷ 36? (a) 50 (b) 500 (c) 5000
  24. 24.√53 to 1 decimal place? (a) 7.3 (b) 7.2 (c) 7.4 (d) 7.5
  25. 25.Best estimate of 692 ÷ 51? (a) 14 (b) 140 (c) 1400
  26. 26.√84 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 9.2 (d) 9.1
  27. 27.Best estimate of 1276 ÷ 48? (a) 26 (b) 2600 (c) 260
  28. 28.Best estimate of 1567 ÷ 56? (a) 2600 (b) 260 (c) 26
  29. 29.√28 to 1 decimal place? (a) 5.4 (b) 5.5 (c) 5.6 (d) 5.3
  30. 30.Best estimate of 4174 ÷ 66? (a) 600 (b) 60 (c) 6000
  31. 31.√98 to 1 decimal place? (a) 9.9 (b) 10.1 (c) 10.0 (d) 10.2
  32. 32.√70 to 1 decimal place? (a) 8.4 (b) 8.1 (c) 8.3 (d) 8.2
  33. 33.√41 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.4 (d) 6.7
  34. 34.Best estimate of 2421 ÷ 32? (a) 8100 (b) 810 (c) 81
  35. 35.Best estimate of 5637 ÷ 61? (a) 9400 (b) 940 (c) 94
  36. 36.√56 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.5 (d) 7.4
  37. 37.√61 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 7.5 (d) 7.6
  38. 38.Best estimate of 1670 ÷ 84? (a) 2100 (b) 210 (c) 21
  39. 39.√51 to 1 decimal place? (a) 7.3 (b) 7.4 (c) 7.2 (d) 7.1
  40. 40.Best estimate of 3284 ÷ 88? (a) 360 (b) 36 (c) 3600

Answer key

  1. 19
  2. 7.9
  3. 30
  4. 82
  5. 35
  6. 16
  7. 104
  8. 62
  9. 66
  10. 49
  11. 9.1
  12. 8.9
  13. 26
  14. 52
  15. 66
  16. 4.9
  17. 5.1
  18. 90
  19. 9.8
  20. 6.1
  21. 90
  22. 13
  23. 50
  24. 7.3
  25. 14
  26. 9.2
  27. 26
  28. 26
  29. 5.3
  30. 60
  31. 9.9
  32. 8.4
  33. 6.4
  34. 81
  35. 94
  36. 7.5
  37. 7.8
  38. 21
  39. 7.1
  40. 36

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