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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 330 · 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.√46 to 1 decimal place? (a) 6.8 (b) 6.6 (c) 6.5 (d) 6.7
  2. 2.Best estimate of 882 ÷ 24? (a) 44 (b) 440 (c) 4400
  3. 3.√27 to 1 decimal place? (a) 5.3 (b) 5.4 (c) 5.1 (d) 5.2
  4. 4.Best estimate of 1136 ÷ 29? (a) 38 (b) 3800 (c) 380
  5. 5.Best estimate of 1368 ÷ 36? (a) 340 (b) 3400 (c) 34
  6. 6.√56 to 1 decimal place? (a) 7.3 (b) 7.5 (c) 7.6 (d) 7.4
  7. 7.√59 to 1 decimal place? (a) 7.9 (b) 7.7 (c) 7.6 (d) 7.8
  8. 8.Best estimate of 1983 ÷ 62? (a) 3300 (b) 33 (c) 330
  9. 9.Best estimate of 1691 ÷ 32? (a) 5600 (b) 56 (c) 560
  10. 10.√58 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.4 (d) 7.5
  11. 11.√87 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.4 (d) 9.3
  12. 12.Best estimate of 2668 ÷ 41? (a) 67 (b) 6700 (c) 670
  13. 13.√53 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.3 (d) 7.5
  14. 14.Best estimate of 2508 ÷ 86? (a) 28 (b) 2800 (c) 280
  15. 15.Best estimate of 685 ÷ 51? (a) 140 (b) 1400 (c) 14
  16. 16.Best estimate of 4306 ÷ 77? (a) 540 (b) 54 (c) 5400
  17. 17.Best estimate of 3602 ÷ 68? (a) 51 (b) 5100 (c) 510
  18. 18.√45 to 1 decimal place? (a) 6.9 (b) 7.0 (c) 6.8 (d) 6.7
  19. 19.Best estimate of 3844 ÷ 76? (a) 4800 (b) 480 (c) 48
  20. 20.Best estimate of 5839 ÷ 78? (a) 730 (b) 7300 (c) 73
  21. 21.Best estimate of 488 ÷ 21? (a) 240 (b) 24 (c) 2400
  22. 22.Best estimate of 3458 ÷ 41? (a) 8600 (b) 86 (c) 860
  23. 23.√66 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.2 (d) 8.1
  24. 24.Best estimate of 4671 ÷ 82? (a) 5800 (b) 580 (c) 58
  25. 25.Best estimate of 784 ÷ 56? (a) 130 (b) 1300 (c) 13
  26. 26.Best estimate of 2140 ÷ 38? (a) 54 (b) 540 (c) 5400
  27. 27.√37 to 1 decimal place? (a) 6.3 (b) 6.2 (c) 6.1 (d) 6.4
  28. 28.√26 to 1 decimal place? (a) 5.2 (b) 4.9 (c) 5.0 (d) 5.1
  29. 29.Best estimate of 6579 ÷ 74? (a) 9400 (b) 940 (c) 94
  30. 30.Best estimate of 4665 ÷ 86? (a) 5200 (b) 52 (c) 520
  31. 31.Best estimate of 2690 ÷ 77? (a) 340 (b) 3400 (c) 34
  32. 32.Best estimate of 427 ÷ 22? (a) 2100 (b) 21 (c) 210
  33. 33.Best estimate of 786 ÷ 38? (a) 20 (b) 200 (c) 2000
  34. 34.Best estimate of 581 ÷ 31? (a) 19 (b) 190 (c) 1900
  35. 35.√80 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 8.7 (d) 8.6
  36. 36.Best estimate of 2636 ÷ 58? (a) 440 (b) 4400 (c) 44
  37. 37.Best estimate of 3858 ÷ 56? (a) 640 (b) 64 (c) 6400
  38. 38.Best estimate of 2435 ÷ 41? (a) 610 (b) 6100 (c) 61
  39. 39.√74 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.9 (d) 8.6
  40. 40.Best estimate of 5186 ÷ 62? (a) 8600 (b) 86 (c) 860

Answer key

  1. 6.8
  2. 44
  3. 5.2
  4. 38
  5. 34
  6. 7.5
  7. 7.7
  8. 33
  9. 56
  10. 7.6
  11. 9.3
  12. 67
  13. 7.3
  14. 28
  15. 14
  16. 54
  17. 51
  18. 6.7
  19. 48
  20. 73
  21. 24
  22. 86
  23. 8.1
  24. 58
  25. 13
  26. 54
  27. 6.1
  28. 5.1
  29. 94
  30. 52
  31. 34
  32. 21
  33. 20
  34. 19
  35. 8.9
  36. 44
  37. 64
  38. 61
  39. 8.6
  40. 86

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