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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 326 · 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 3556 ÷ 66? (a) 510 (b) 51 (c) 5100
  2. 2.Best estimate of 2528 ÷ 71? (a) 3600 (b) 36 (c) 360
  3. 3.√27 to 1 decimal place? (a) 5.4 (b) 5.1 (c) 5.3 (d) 5.2
  4. 4.√31 to 1 decimal place? (a) 5.5 (b) 5.7 (c) 5.6 (d) 5.8
  5. 5.Best estimate of 2190 ÷ 64? (a) 3700 (b) 370 (c) 37
  6. 6.Best estimate of 2479 ÷ 33? (a) 8300 (b) 83 (c) 830
  7. 7.√83 to 1 decimal place? (a) 9.1 (b) 9.4 (c) 9.3 (d) 9.2
  8. 8.Best estimate of 4927 ÷ 58? (a) 820 (b) 82 (c) 8200
  9. 9.Best estimate of 3234 ÷ 49? (a) 6500 (b) 65 (c) 650
  10. 10.Best estimate of 1918 ÷ 76? (a) 2400 (b) 24 (c) 240
  11. 11.√51 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.3 (d) 7.0
  12. 12.Best estimate of 3183 ÷ 52? (a) 640 (b) 6400 (c) 64
  13. 13.Best estimate of 4436 ÷ 51? (a) 890 (b) 8900 (c) 89
  14. 14.Best estimate of 4760 ÷ 57? (a) 790 (b) 79 (c) 7900
  15. 15.Best estimate of 4694 ÷ 69? (a) 670 (b) 6700 (c) 67
  16. 16.Best estimate of 1584 ÷ 34? (a) 53 (b) 530 (c) 5300
  17. 17.Best estimate of 3795 ÷ 61? (a) 630 (b) 6300 (c) 63
  18. 18.Best estimate of 958 ÷ 26? (a) 320 (b) 32 (c) 3200
  19. 19.Best estimate of 1485 ÷ 51? (a) 300 (b) 3000 (c) 30
  20. 20.√37 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 6.3 (d) 6.0
  21. 21.√61 to 1 decimal place? (a) 8.0 (b) 7.8 (c) 7.9 (d) 7.7
  22. 22.√92 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.5 (d) 9.6
  23. 23.Best estimate of 5503 ÷ 83? (a) 690 (b) 6900 (c) 69
  24. 24.Best estimate of 3075 ÷ 42? (a) 7700 (b) 770 (c) 77
  25. 25.Best estimate of 1820 ÷ 54? (a) 36 (b) 3600 (c) 360
  26. 26.√26 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.1 (d) 5.2
  27. 27.Best estimate of 1253 ÷ 24? (a) 6300 (b) 630 (c) 63
  28. 28.Best estimate of 1688 ÷ 84? (a) 2100 (b) 210 (c) 21
  29. 29.Best estimate of 1143 ÷ 29? (a) 380 (b) 3800 (c) 38
  30. 30.√78 to 1 decimal place? (a) 9.1 (b) 8.9 (c) 8.8 (d) 9.0
  31. 31.Best estimate of 1015 ÷ 62? (a) 1700 (b) 170 (c) 17
  32. 32.Best estimate of 2665 ÷ 42? (a) 670 (b) 67 (c) 6700
  33. 33.√85 to 1 decimal place? (a) 9.2 (b) 9.0 (c) 8.9 (d) 9.1
  34. 34.Best estimate of 3413 ÷ 46? (a) 680 (b) 6800 (c) 68
  35. 35.Best estimate of 2448 ÷ 27? (a) 820 (b) 82 (c) 8200
  36. 36.Best estimate of 6596 ÷ 72? (a) 940 (b) 94 (c) 9400
  37. 37.Best estimate of 2523 ÷ 42? (a) 63 (b) 630 (c) 6300
  38. 38.√20 to 1 decimal place? (a) 4.2 (b) 4.3 (c) 4.4 (d) 4.5
  39. 39.√89 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.3 (d) 9.2
  40. 40.√32 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.5 (d) 5.4

Answer key

  1. 51
  2. 36
  3. 5.2
  4. 5.6
  5. 37
  6. 83
  7. 9.1
  8. 82
  9. 65
  10. 24
  11. 7.1
  12. 64
  13. 89
  14. 79
  15. 67
  16. 53
  17. 63
  18. 32
  19. 30
  20. 6.1
  21. 7.8
  22. 9.6
  23. 69
  24. 77
  25. 36
  26. 5.1
  27. 63
  28. 21
  29. 38
  30. 8.8
  31. 17
  32. 67
  33. 9.2
  34. 68
  35. 82
  36. 94
  37. 63
  38. 4.5
  39. 9.4
  40. 5.7

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