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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 83 · 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 4335 ÷ 49? (a) 87 (b) 8700 (c) 870
  2. 2.Best estimate of 3034 ÷ 38? (a) 76 (b) 7600 (c) 760
  3. 3.Best estimate of 3905 ÷ 64? (a) 6500 (b) 65 (c) 650
  4. 4.Best estimate of 1868 ÷ 59? (a) 3100 (b) 31 (c) 310
  5. 5.Best estimate of 2468 ÷ 54? (a) 490 (b) 49 (c) 4900
  6. 6.√80 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 8.9 (d) 9.0
  7. 7.√58 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 7.6 (d) 7.7
  8. 8.Best estimate of 1020 ÷ 39? (a) 2600 (b) 26 (c) 260
  9. 9.Best estimate of 1581 ÷ 53? (a) 320 (b) 32 (c) 3200
  10. 10.√42 to 1 decimal place? (a) 6.4 (b) 6.5 (c) 6.7 (d) 6.6
  11. 11.√23 to 1 decimal place? (a) 4.7 (b) 4.9 (c) 4.8 (d) 4.6
  12. 12.Best estimate of 3109 ÷ 59? (a) 520 (b) 52 (c) 5200
  13. 13.Best estimate of 1323 ÷ 34? (a) 4400 (b) 440 (c) 44
  14. 14.√55 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.2 (d) 7.1
  15. 15.√37 to 1 decimal place? (a) 6.1 (b) 6.3 (c) 6.0 (d) 6.2
  16. 16.Best estimate of 1629 ÷ 71? (a) 230 (b) 23 (c) 2300
  17. 17.√96 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.8 (d) 9.5
  18. 18.Best estimate of 3349 ÷ 83? (a) 4200 (b) 42 (c) 420
  19. 19.Best estimate of 2091 ÷ 38? (a) 52 (b) 520 (c) 5200
  20. 20.√31 to 1 decimal place? (a) 5.7 (b) 5.8 (c) 5.9 (d) 5.6
  21. 21.Best estimate of 1356 ÷ 44? (a) 340 (b) 3400 (c) 34
  22. 22.Best estimate of 1997 ÷ 86? (a) 220 (b) 22 (c) 2200
  23. 23.Best estimate of 1979 ÷ 27? (a) 660 (b) 6600 (c) 66
  24. 24.Best estimate of 1743 ÷ 26? (a) 5800 (b) 58 (c) 580
  25. 25.Best estimate of 3827 ÷ 76? (a) 48 (b) 4800 (c) 480
  26. 26.√92 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.4 (d) 9.5
  27. 27.√74 to 1 decimal place? (a) 8.9 (b) 8.6 (c) 8.7 (d) 8.8
  28. 28.Best estimate of 5419 ÷ 64? (a) 9000 (b) 90 (c) 900
  29. 29.√61 to 1 decimal place? (a) 8.0 (b) 7.7 (c) 7.9 (d) 7.8
  30. 30.Best estimate of 877 ÷ 71? (a) 13 (b) 1300 (c) 130
  31. 31.√48 to 1 decimal place? (a) 6.8 (b) 7.1 (c) 7.0 (d) 6.9
  32. 32.√82 to 1 decimal place? (a) 8.8 (b) 9.1 (c) 8.9 (d) 9.0
  33. 33.Best estimate of 621 ÷ 27? (a) 2100 (b) 21 (c) 210
  34. 34.Best estimate of 2636 ÷ 82? (a) 33 (b) 330 (c) 3300
  35. 35.Best estimate of 1461 ÷ 44? (a) 37 (b) 3700 (c) 370
  36. 36.√29 to 1 decimal place? (a) 5.5 (b) 5.4 (c) 5.3 (d) 5.6
  37. 37.√79 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 9.1 (d) 8.8
  38. 38.Best estimate of 3463 ÷ 42? (a) 870 (b) 8700 (c) 87
  39. 39.Best estimate of 2697 ÷ 48? (a) 54 (b) 5400 (c) 540
  40. 40.Best estimate of 3664 ÷ 73? (a) 520 (b) 52 (c) 5200

Answer key

  1. 87
  2. 76
  3. 65
  4. 31
  5. 49
  6. 8.9
  7. 7.6
  8. 26
  9. 32
  10. 6.5
  11. 4.8
  12. 52
  13. 44
  14. 7.4
  15. 6.1
  16. 23
  17. 9.8
  18. 42
  19. 52
  20. 5.6
  21. 34
  22. 22
  23. 66
  24. 58
  25. 48
  26. 9.6
  27. 8.6
  28. 90
  29. 7.8
  30. 13
  31. 6.9
  32. 9.1
  33. 21
  34. 33
  35. 37
  36. 5.4
  37. 8.9
  38. 87
  39. 54
  40. 52

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