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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 230 · 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.√34 to 1 decimal place? (a) 5.5 (b) 5.7 (c) 5.8 (d) 5.6
  2. 2.Best estimate of 1286 ÷ 66? (a) 18 (b) 180 (c) 1800
  3. 3.√94 to 1 decimal place? (a) 9.4 (b) 9.7 (c) 9.6 (d) 9.5
  4. 4.√69 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.4 (d) 8.5
  5. 5.√21 to 1 decimal place? (a) 4.9 (b) 4.8 (c) 4.7 (d) 4.6
  6. 6.Best estimate of 591 ÷ 32? (a) 200 (b) 2000 (c) 20
  7. 7.Best estimate of 893 ÷ 46? (a) 18 (b) 180 (c) 1800
  8. 8.√61 to 1 decimal place? (a) 7.9 (b) 7.8 (c) 7.7 (d) 7.6
  9. 9.Best estimate of 3136 ÷ 41? (a) 7800 (b) 780 (c) 78
  10. 10.Best estimate of 6743 ÷ 74? (a) 9600 (b) 960 (c) 96
  11. 11.Best estimate of 592 ÷ 26? (a) 20 (b) 2000 (c) 200
  12. 12.Best estimate of 479 ÷ 32? (a) 16 (b) 160 (c) 1600
  13. 13.Best estimate of 3408 ÷ 42? (a) 850 (b) 85 (c) 8500
  14. 14.√79 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 8.9 (d) 8.8
  15. 15.√38 to 1 decimal place? (a) 6.3 (b) 6.1 (c) 6.2 (d) 6.0
  16. 16.Best estimate of 1882 ÷ 62? (a) 31 (b) 310 (c) 3100
  17. 17.Best estimate of 1281 ÷ 82? (a) 1600 (b) 160 (c) 16
  18. 18.Best estimate of 387 ÷ 32? (a) 1300 (b) 130 (c) 13
  19. 19.√67 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.1 (d) 8.2
  20. 20.Best estimate of 525 ÷ 26? (a) 18 (b) 1800 (c) 180
  21. 21.√90 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.2 (d) 9.3
  22. 22.√23 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 5.0 (d) 4.9
  23. 23.√88 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.4 (d) 9.5
  24. 24.√52 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.0 (d) 7.1
  25. 25.Best estimate of 1679 ÷ 62? (a) 28 (b) 280 (c) 2800
  26. 26.Best estimate of 1095 ÷ 26? (a) 37 (b) 3700 (c) 370
  27. 27.Best estimate of 2606 ÷ 48? (a) 520 (b) 52 (c) 5200
  28. 28.√76 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.4 (d) 8.7
  29. 29.Best estimate of 1818 ÷ 24? (a) 910 (b) 9100 (c) 91
  30. 30.Best estimate of 1490 ÷ 52? (a) 3000 (b) 300 (c) 30
  31. 31.√87 to 1 decimal place? (a) 9.4 (b) 9.1 (c) 9.3 (d) 9.2
  32. 32.Best estimate of 2192 ÷ 89? (a) 24 (b) 2400 (c) 240
  33. 33.Best estimate of 2139 ÷ 88? (a) 24 (b) 2400 (c) 240
  34. 34.Best estimate of 7983 ÷ 88? (a) 8900 (b) 89 (c) 890
  35. 35.Best estimate of 3163 ÷ 72? (a) 4500 (b) 45 (c) 450
  36. 36.√26 to 1 decimal place? (a) 5.1 (b) 5.4 (c) 5.3 (d) 5.2
  37. 37.Best estimate of 1687 ÷ 34? (a) 560 (b) 5600 (c) 56
  38. 38.√98 to 1 decimal place? (a) 9.8 (b) 10.0 (c) 9.7 (d) 9.9
  39. 39.Best estimate of 3400 ÷ 62? (a) 5700 (b) 570 (c) 57
  40. 40.Best estimate of 2575 ÷ 72? (a) 3700 (b) 370 (c) 37

Answer key

  1. 5.8
  2. 18
  3. 9.7
  4. 8.3
  5. 4.6
  6. 20
  7. 18
  8. 7.8
  9. 78
  10. 96
  11. 20
  12. 16
  13. 85
  14. 8.9
  15. 6.2
  16. 31
  17. 16
  18. 13
  19. 8.2
  20. 18
  21. 9.5
  22. 4.8
  23. 9.4
  24. 7.2
  25. 28
  26. 37
  27. 52
  28. 8.7
  29. 91
  30. 30
  31. 9.3
  32. 24
  33. 24
  34. 89
  35. 45
  36. 5.1
  37. 56
  38. 9.9
  39. 57
  40. 37

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