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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 136 · 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 449 ÷ 26? (a) 1500 (b) 15 (c) 150
  2. 2.Best estimate of 2305 ÷ 31? (a) 77 (b) 770 (c) 7700
  3. 3.√21 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 4.9 (d) 4.6
  4. 4.√71 to 1 decimal place? (a) 8.4 (b) 8.2 (c) 8.3 (d) 8.5
  5. 5.√51 to 1 decimal place? (a) 7.3 (b) 7.2 (c) 7.1 (d) 7.4
  6. 6.Best estimate of 3488 ÷ 66? (a) 5000 (b) 50 (c) 500
  7. 7.Best estimate of 573 ÷ 26? (a) 19 (b) 1900 (c) 190
  8. 8.√70 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.2 (d) 8.5
  9. 9.√31 to 1 decimal place? (a) 5.3 (b) 5.6 (c) 5.5 (d) 5.4
  10. 10.√37 to 1 decimal place? (a) 6.0 (b) 6.1 (c) 6.3 (d) 6.2
  11. 11.Best estimate of 1624 ÷ 57? (a) 27 (b) 2700 (c) 270
  12. 12.Best estimate of 2318 ÷ 79? (a) 290 (b) 2900 (c) 29
  13. 13.Best estimate of 2653 ÷ 39? (a) 66 (b) 6600 (c) 660
  14. 14.√58 to 1 decimal place? (a) 7.6 (b) 7.5 (c) 7.3 (d) 7.4
  15. 15.Best estimate of 4343 ÷ 62? (a) 72 (b) 7200 (c) 720
  16. 16.Best estimate of 2481 ÷ 82? (a) 31 (b) 3100 (c) 310
  17. 17.√90 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.4 (d) 9.6
  18. 18.Best estimate of 4419 ÷ 87? (a) 4900 (b) 49 (c) 490
  19. 19.Best estimate of 3038 ÷ 54? (a) 6100 (b) 610 (c) 61
  20. 20.Best estimate of 1234 ÷ 31? (a) 410 (b) 41 (c) 4100
  21. 21.Best estimate of 1985 ÷ 58? (a) 330 (b) 33 (c) 3300
  22. 22.Best estimate of 1419 ÷ 61? (a) 24 (b) 240 (c) 2400
  23. 23.√59 to 1 decimal place? (a) 7.6 (b) 7.5 (c) 7.4 (d) 7.7
  24. 24.Best estimate of 5555 ÷ 62? (a) 9300 (b) 93 (c) 930
  25. 25.√67 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.5 (d) 8.2
  26. 26.√61 to 1 decimal place? (a) 7.6 (b) 7.8 (c) 7.7 (d) 7.9
  27. 27.√79 to 1 decimal place? (a) 8.9 (b) 9.2 (c) 9.0 (d) 9.1
  28. 28.√24 to 1 decimal place? (a) 4.9 (b) 5.1 (c) 4.8 (d) 5.0
  29. 29.√69 to 1 decimal place? (a) 8.3 (b) 8.6 (c) 8.4 (d) 8.5
  30. 30.Best estimate of 2380 ÷ 32? (a) 79 (b) 7900 (c) 790
  31. 31.√26 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 5.1 (d) 4.8
  32. 32.Best estimate of 1092 ÷ 24? (a) 55 (b) 550 (c) 5500
  33. 33.Best estimate of 734 ÷ 26? (a) 2400 (b) 240 (c) 24
  34. 34.Best estimate of 695 ÷ 28? (a) 23 (b) 230 (c) 2300
  35. 35.Best estimate of 1753 ÷ 24? (a) 8800 (b) 880 (c) 88
  36. 36.Best estimate of 1822 ÷ 33? (a) 61 (b) 610 (c) 6100
  37. 37.Best estimate of 3346 ÷ 44? (a) 8400 (b) 84 (c) 840
  38. 38.Best estimate of 4110 ÷ 78? (a) 510 (b) 5100 (c) 51
  39. 39.√83 to 1 decimal place? (a) 9.0 (b) 9.2 (c) 9.1 (d) 9.3
  40. 40.Best estimate of 1110 ÷ 74? (a) 160 (b) 16 (c) 1600

Answer key

  1. 15
  2. 77
  3. 4.6
  4. 8.4
  5. 7.1
  6. 50
  7. 19
  8. 8.4
  9. 5.6
  10. 6.1
  11. 27
  12. 29
  13. 66
  14. 7.6
  15. 72
  16. 31
  17. 9.5
  18. 49
  19. 61
  20. 41
  21. 33
  22. 24
  23. 7.7
  24. 93
  25. 8.2
  26. 7.8
  27. 8.9
  28. 4.9
  29. 8.3
  30. 79
  31. 5.1
  32. 55
  33. 24
  34. 23
  35. 88
  36. 61
  37. 84
  38. 51
  39. 9.1
  40. 16

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