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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 664 · 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 1179 ÷ 43? (a) 290 (b) 2900 (c) 29
  2. 2.√58 to 1 decimal place? (a) 7.3 (b) 7.4 (c) 7.5 (d) 7.6
  3. 3.Best estimate of 2674 ÷ 46? (a) 530 (b) 5300 (c) 53
  4. 4.Best estimate of 1280 ÷ 72? (a) 1800 (b) 180 (c) 18
  5. 5.Best estimate of 711 ÷ 37? (a) 18 (b) 1800 (c) 180
  6. 6.Best estimate of 1285 ÷ 71? (a) 180 (b) 1800 (c) 18
  7. 7.√94 to 1 decimal place? (a) 9.5 (b) 9.8 (c) 9.7 (d) 9.6
  8. 8.Best estimate of 1463 ÷ 22? (a) 7300 (b) 73 (c) 730
  9. 9.√69 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.3 (d) 8.4
  10. 10.Best estimate of 4193 ÷ 53? (a) 84 (b) 8400 (c) 840
  11. 11.√85 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 9.2 (d) 9.1
  12. 12.√31 to 1 decimal place? (a) 5.7 (b) 5.8 (c) 5.6 (d) 5.5
  13. 13.√88 to 1 decimal place? (a) 9.3 (b) 9.6 (c) 9.4 (d) 9.5
  14. 14.Best estimate of 5884 ÷ 89? (a) 650 (b) 65 (c) 6500
  15. 15.√66 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 8.2 (d) 8.3
  16. 16.Best estimate of 1151 ÷ 46? (a) 2300 (b) 23 (c) 230
  17. 17.√50 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 6.9 (d) 7.0
  18. 18.√40 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 6.4 (d) 6.3
  19. 19.√61 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 8.0 (d) 8.1
  20. 20.√26 to 1 decimal place? (a) 5.3 (b) 5.4 (c) 5.1 (d) 5.2
  21. 21.√42 to 1 decimal place? (a) 6.6 (b) 6.8 (c) 6.5 (d) 6.7
  22. 22.Best estimate of 6475 ÷ 83? (a) 810 (b) 81 (c) 8100
  23. 23.√28 to 1 decimal place? (a) 5.3 (b) 5.1 (c) 5.4 (d) 5.2
  24. 24.√82 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.0 (d) 9.3
  25. 25.√20 to 1 decimal place? (a) 4.3 (b) 4.4 (c) 4.5 (d) 4.2
  26. 26.Best estimate of 1861 ÷ 43? (a) 4700 (b) 47 (c) 470
  27. 27.Best estimate of 3797 ÷ 64? (a) 630 (b) 6300 (c) 63
  28. 28.Best estimate of 856 ÷ 49? (a) 170 (b) 1700 (c) 17
  29. 29.Best estimate of 2101 ÷ 26? (a) 70 (b) 700 (c) 7000
  30. 30.√44 to 1 decimal place? (a) 6.9 (b) 6.7 (c) 6.6 (d) 6.8
  31. 31.√63 to 1 decimal place? (a) 7.7 (b) 7.9 (c) 7.8 (d) 7.6
  32. 32.Best estimate of 1170 ÷ 52? (a) 230 (b) 23 (c) 2300
  33. 33.Best estimate of 2207 ÷ 73? (a) 32 (b) 3200 (c) 320
  34. 34.Best estimate of 7465 ÷ 83? (a) 9300 (b) 93 (c) 930
  35. 35.Best estimate of 533 ÷ 21? (a) 270 (b) 2700 (c) 27
  36. 36.Best estimate of 1608 ÷ 26? (a) 540 (b) 54 (c) 5400
  37. 37.Best estimate of 1866 ÷ 36? (a) 470 (b) 4700 (c) 47
  38. 38.Best estimate of 2207 ÷ 46? (a) 440 (b) 4400 (c) 44
  39. 39.Best estimate of 3416 ÷ 36? (a) 8500 (b) 850 (c) 85
  40. 40.Best estimate of 3124 ÷ 41? (a) 7800 (b) 780 (c) 78

Answer key

  1. 29
  2. 7.6
  3. 53
  4. 18
  5. 18
  6. 18
  7. 9.7
  8. 73
  9. 8.3
  10. 84
  11. 9.2
  12. 5.6
  13. 9.4
  14. 65
  15. 8.1
  16. 23
  17. 7.1
  18. 6.3
  19. 7.8
  20. 5.1
  21. 6.5
  22. 81
  23. 5.3
  24. 9.1
  25. 4.5
  26. 47
  27. 63
  28. 17
  29. 70
  30. 6.6
  31. 7.9
  32. 23
  33. 32
  34. 93
  35. 27
  36. 54
  37. 47
  38. 44
  39. 85
  40. 78

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