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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 590 · 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.√59 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.4 (d) 7.5
  2. 2.Best estimate of 6504 ÷ 69? (a) 9300 (b) 93 (c) 930
  3. 3.√87 to 1 decimal place? (a) 9.5 (b) 9.2 (c) 9.4 (d) 9.3
  4. 4.√56 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.3 (d) 7.4
  5. 5.Best estimate of 1328 ÷ 24? (a) 6600 (b) 660 (c) 66
  6. 6.√84 to 1 decimal place? (a) 9.3 (b) 9.5 (c) 9.2 (d) 9.4
  7. 7.Best estimate of 2252 ÷ 26? (a) 75 (b) 7500 (c) 750
  8. 8.Best estimate of 812 ÷ 36? (a) 2000 (b) 200 (c) 20
  9. 9.√82 to 1 decimal place? (a) 8.8 (b) 9.1 (c) 8.9 (d) 9.0
  10. 10.√42 to 1 decimal place? (a) 6.7 (b) 6.4 (c) 6.5 (d) 6.6
  11. 11.√20 to 1 decimal place? (a) 4.7 (b) 4.5 (c) 4.8 (d) 4.6
  12. 12.Best estimate of 547 ÷ 26? (a) 18 (b) 180 (c) 1800
  13. 13.Best estimate of 1361 ÷ 34? (a) 4500 (b) 45 (c) 450
  14. 14.Best estimate of 1967 ÷ 22? (a) 980 (b) 98 (c) 9800
  15. 15.Best estimate of 2763 ÷ 52? (a) 55 (b) 5500 (c) 550
  16. 16.√23 to 1 decimal place? (a) 4.8 (b) 4.9 (c) 4.6 (d) 4.7
  17. 17.√26 to 1 decimal place? (a) 5.1 (b) 5.3 (c) 5.2 (d) 5.4
  18. 18.Best estimate of 3057 ÷ 69? (a) 440 (b) 44 (c) 4400
  19. 19.Best estimate of 3023 ÷ 32? (a) 1010 (b) 101 (c) 10100
  20. 20.√58 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.7 (d) 7.5
  21. 21.Best estimate of 1879 ÷ 64? (a) 310 (b) 31 (c) 3100
  22. 22.Best estimate of 2754 ÷ 32? (a) 920 (b) 9200 (c) 92
  23. 23.√66 to 1 decimal place? (a) 8.1 (b) 8.3 (c) 8.0 (d) 8.2
  24. 24.Best estimate of 1605 ÷ 52? (a) 32 (b) 3200 (c) 320
  25. 25.Best estimate of 5290 ÷ 61? (a) 88 (b) 880 (c) 8800
  26. 26.Best estimate of 713 ÷ 33? (a) 240 (b) 2400 (c) 24
  27. 27.√96 to 1 decimal place? (a) 9.8 (b) 9.5 (c) 9.7 (d) 9.6
  28. 28.√27 to 1 decimal place? (a) 5.3 (b) 5.0 (c) 5.1 (d) 5.2
  29. 29.√78 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 9.0 (d) 8.9
  30. 30.√76 to 1 decimal place? (a) 8.5 (b) 8.7 (c) 8.6 (d) 8.4
  31. 31.√71 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.7 (d) 8.6
  32. 32.√38 to 1 decimal place? (a) 6.2 (b) 6.1 (c) 6.0 (d) 6.3
  33. 33.Best estimate of 6234 ÷ 72? (a) 8900 (b) 89 (c) 890
  34. 34.√40 to 1 decimal place? (a) 6.1 (b) 6.3 (c) 6.2 (d) 6.0
  35. 35.Best estimate of 1026 ÷ 58? (a) 170 (b) 1700 (c) 17
  36. 36.√55 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.4 (d) 7.1
  37. 37.√79 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 9.0 (d) 8.7
  38. 38.√98 to 1 decimal place? (a) 9.9 (b) 10.1 (c) 10.0 (d) 9.8
  39. 39.Best estimate of 2701 ÷ 86? (a) 300 (b) 30 (c) 3000
  40. 40.√46 to 1 decimal place? (a) 6.7 (b) 6.9 (c) 6.8 (d) 7.0

Answer key

  1. 7.7
  2. 93
  3. 9.3
  4. 7.5
  5. 66
  6. 9.2
  7. 75
  8. 20
  9. 9.1
  10. 6.5
  11. 4.5
  12. 18
  13. 45
  14. 98
  15. 55
  16. 4.8
  17. 5.1
  18. 44
  19. 101
  20. 7.6
  21. 31
  22. 92
  23. 8.1
  24. 32
  25. 88
  26. 24
  27. 9.8
  28. 5.2
  29. 8.8
  30. 8.7
  31. 8.4
  32. 6.2
  33. 89
  34. 6.3
  35. 17
  36. 7.4
  37. 8.9
  38. 9.9
  39. 30
  40. 6.8

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