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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 776 · 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 1994 ÷ 69? (a) 28 (b) 280 (c) 2800
  2. 2.Best estimate of 4971 ÷ 54? (a) 990 (b) 9900 (c) 99
  3. 3.Best estimate of 4317 ÷ 74? (a) 6200 (b) 620 (c) 62
  4. 4.Best estimate of 2620 ÷ 64? (a) 440 (b) 4400 (c) 44
  5. 5.Best estimate of 692 ÷ 29? (a) 230 (b) 23 (c) 2300
  6. 6.Best estimate of 1348 ÷ 62? (a) 220 (b) 2200 (c) 22
  7. 7.√22 to 1 decimal place? (a) 4.5 (b) 4.6 (c) 4.8 (d) 4.7
  8. 8.√21 to 1 decimal place? (a) 4.7 (b) 4.6 (c) 4.8 (d) 4.5
  9. 9.Best estimate of 1432 ÷ 31? (a) 48 (b) 4800 (c) 480
  10. 10.Best estimate of 4343 ÷ 49? (a) 87 (b) 8700 (c) 870
  11. 11.√72 to 1 decimal place? (a) 8.6 (b) 8.8 (c) 8.7 (d) 8.5
  12. 12.√90 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.6 (d) 9.3
  13. 13.Best estimate of 1119 ÷ 54? (a) 220 (b) 2200 (c) 22
  14. 14.Best estimate of 7140 ÷ 77? (a) 89 (b) 8900 (c) 890
  15. 15.Best estimate of 4354 ÷ 53? (a) 8700 (b) 870 (c) 87
  16. 16.Best estimate of 3497 ÷ 84? (a) 4400 (b) 440 (c) 44
  17. 17.√69 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 8.3 (d) 8.4
  18. 18.Best estimate of 3373 ÷ 54? (a) 67 (b) 670 (c) 6700
  19. 19.√50 to 1 decimal place? (a) 7.0 (b) 7.2 (c) 6.9 (d) 7.1
  20. 20.√65 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 8.3 (d) 8.4
  21. 21.√29 to 1 decimal place? (a) 5.4 (b) 5.6 (c) 5.3 (d) 5.5
  22. 22.Best estimate of 1316 ÷ 22? (a) 6600 (b) 660 (c) 66
  23. 23.√26 to 1 decimal place? (a) 4.8 (b) 5.1 (c) 5.0 (d) 4.9
  24. 24.Best estimate of 1240 ÷ 34? (a) 4100 (b) 410 (c) 41
  25. 25.√41 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.2 (d) 6.5
  26. 26.Best estimate of 2900 ÷ 33? (a) 970 (b) 97 (c) 9700
  27. 27.Best estimate of 2079 ÷ 44? (a) 5200 (b) 520 (c) 52
  28. 28.Best estimate of 3951 ÷ 69? (a) 56 (b) 560 (c) 5600
  29. 29.Best estimate of 719 ÷ 36? (a) 1800 (b) 180 (c) 18
  30. 30.√28 to 1 decimal place? (a) 5.1 (b) 5.0 (c) 5.3 (d) 5.2
  31. 31.Best estimate of 5950 ÷ 67? (a) 85 (b) 850 (c) 8500
  32. 32.Best estimate of 3113 ÷ 62? (a) 52 (b) 520 (c) 5200
  33. 33.Best estimate of 1113 ÷ 51? (a) 22 (b) 2200 (c) 220
  34. 34.Best estimate of 4029 ÷ 69? (a) 580 (b) 58 (c) 5800
  35. 35.√59 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 7.6 (d) 7.9
  36. 36.√98 to 1 decimal place? (a) 10.0 (b) 9.9 (c) 10.1 (d) 10.2
  37. 37.Best estimate of 3875 ÷ 66? (a) 55 (b) 5500 (c) 550
  38. 38.Best estimate of 5939 ÷ 86? (a) 660 (b) 6600 (c) 66
  39. 39.√67 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.0 (d) 8.1
  40. 40.√87 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.1 (d) 9.0

Answer key

  1. 28
  2. 99
  3. 62
  4. 44
  5. 23
  6. 22
  7. 4.7
  8. 4.6
  9. 48
  10. 87
  11. 8.5
  12. 9.5
  13. 22
  14. 89
  15. 87
  16. 44
  17. 8.3
  18. 67
  19. 7.1
  20. 8.1
  21. 5.4
  22. 66
  23. 5.1
  24. 41
  25. 6.4
  26. 97
  27. 52
  28. 56
  29. 18
  30. 5.3
  31. 85
  32. 52
  33. 22
  34. 58
  35. 7.7
  36. 9.9
  37. 55
  38. 66
  39. 8.2
  40. 9.3

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