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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 286 · 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 1617 ÷ 42? (a) 400 (b) 40 (c) 4000
  2. 2.Best estimate of 1427 ÷ 56? (a) 2400 (b) 24 (c) 240
  3. 3.Best estimate of 2593 ÷ 66? (a) 370 (b) 3700 (c) 37
  4. 4.√20 to 1 decimal place? (a) 4.5 (b) 4.4 (c) 4.6 (d) 4.3
  5. 5.Best estimate of 4753 ÷ 87? (a) 53 (b) 5300 (c) 530
  6. 6.Best estimate of 3172 ÷ 49? (a) 63 (b) 6300 (c) 630
  7. 7.Best estimate of 2410 ÷ 66? (a) 34 (b) 340 (c) 3400
  8. 8.√30 to 1 decimal place? (a) 5.8 (b) 5.5 (c) 5.6 (d) 5.7
  9. 9.Best estimate of 3156 ÷ 34? (a) 105 (b) 1050 (c) 10500
  10. 10.Best estimate of 4059 ÷ 56? (a) 68 (b) 6800 (c) 680
  11. 11.√26 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.1 (d) 5.0
  12. 12.Best estimate of 2473 ÷ 61? (a) 410 (b) 41 (c) 4100
  13. 13.√40 to 1 decimal place? (a) 6.5 (b) 6.3 (c) 6.2 (d) 6.4
  14. 14.Best estimate of 2084 ÷ 24? (a) 104 (b) 10400 (c) 1040
  15. 15.√29 to 1 decimal place? (a) 5.3 (b) 5.2 (c) 5.5 (d) 5.4
  16. 16.Best estimate of 886 ÷ 46? (a) 180 (b) 1800 (c) 18
  17. 17.Best estimate of 5320 ÷ 72? (a) 7600 (b) 76 (c) 760
  18. 18.Best estimate of 1390 ÷ 27? (a) 46 (b) 460 (c) 4600
  19. 19.Best estimate of 5754 ÷ 89? (a) 640 (b) 6400 (c) 64
  20. 20.Best estimate of 5333 ÷ 72? (a) 76 (b) 7600 (c) 760
  21. 21.Best estimate of 3074 ÷ 48? (a) 610 (b) 6100 (c) 61
  22. 22.Best estimate of 2874 ÷ 31? (a) 96 (b) 960 (c) 9600
  23. 23.Best estimate of 1197 ÷ 26? (a) 400 (b) 40 (c) 4000
  24. 24.Best estimate of 6554 ÷ 76? (a) 8200 (b) 820 (c) 82
  25. 25.√59 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.8 (d) 7.5
  26. 26.√58 to 1 decimal place? (a) 7.9 (b) 7.6 (c) 7.8 (d) 7.7
  27. 27.Best estimate of 6391 ÷ 72? (a) 910 (b) 91 (c) 9100
  28. 28.√83 to 1 decimal place? (a) 9.1 (b) 9.3 (c) 9.2 (d) 9.0
  29. 29.Best estimate of 643 ÷ 36? (a) 16 (b) 160 (c) 1600
  30. 30.√41 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.6 (d) 6.5
  31. 31.√52 to 1 decimal place? (a) 7.4 (b) 7.2 (c) 7.3 (d) 7.5
  32. 32.√76 to 1 decimal place? (a) 8.5 (b) 8.4 (c) 8.7 (d) 8.6
  33. 33.Best estimate of 944 ÷ 21? (a) 470 (b) 47 (c) 4700
  34. 34.Best estimate of 913 ÷ 21? (a) 460 (b) 4600 (c) 46
  35. 35.√74 to 1 decimal place? (a) 8.6 (b) 8.8 (c) 8.7 (d) 8.9
  36. 36.Best estimate of 3886 ÷ 72? (a) 560 (b) 5600 (c) 56
  37. 37.Best estimate of 3697 ÷ 66? (a) 530 (b) 53 (c) 5300
  38. 38.Best estimate of 687 ÷ 38? (a) 1700 (b) 170 (c) 17
  39. 39.√31 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.4 (d) 5.3
  40. 40.Best estimate of 645 ÷ 34? (a) 220 (b) 2200 (c) 22

Answer key

  1. 40
  2. 24
  3. 37
  4. 4.5
  5. 53
  6. 63
  7. 34
  8. 5.5
  9. 105
  10. 68
  11. 5.1
  12. 41
  13. 6.3
  14. 104
  15. 5.4
  16. 18
  17. 76
  18. 46
  19. 64
  20. 76
  21. 61
  22. 96
  23. 40
  24. 82
  25. 7.7
  26. 7.6
  27. 91
  28. 9.1
  29. 16
  30. 6.4
  31. 7.2
  32. 8.7
  33. 47
  34. 46
  35. 8.6
  36. 56
  37. 53
  38. 17
  39. 5.6
  40. 22

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