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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 911 · 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 642 ÷ 41? (a) 16 (b) 160 (c) 1600
  2. 2.√61 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 7.7 (d) 8.0
  3. 3.√94 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 10.0 (d) 9.7
  4. 4.Best estimate of 1324 ÷ 26? (a) 4400 (b) 44 (c) 440
  5. 5.√35 to 1 decimal place? (a) 5.7 (b) 5.8 (c) 5.9 (d) 5.6
  6. 6.Best estimate of 2942 ÷ 89? (a) 3300 (b) 330 (c) 33
  7. 7.√78 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 9.1 (d) 9.0
  8. 8.√34 to 1 decimal place? (a) 5.8 (b) 6.1 (c) 5.9 (d) 6.0
  9. 9.√50 to 1 decimal place? (a) 7.3 (b) 7.1 (c) 7.0 (d) 7.2
  10. 10.Best estimate of 2774 ÷ 38? (a) 69 (b) 690 (c) 6900
  11. 11.√71 to 1 decimal place? (a) 8.2 (b) 8.5 (c) 8.4 (d) 8.3
  12. 12.√38 to 1 decimal place? (a) 5.9 (b) 6.1 (c) 6.0 (d) 6.2
  13. 13.Best estimate of 1237 ÷ 56? (a) 21 (b) 210 (c) 2100
  14. 14.√59 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 7.9 (d) 7.6
  15. 15.Best estimate of 1672 ÷ 36? (a) 42 (b) 420 (c) 4200
  16. 16.√31 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.4 (d) 5.3
  17. 17.Best estimate of 1369 ÷ 21? (a) 68 (b) 6800 (c) 680
  18. 18.√20 to 1 decimal place? (a) 4.2 (b) 4.4 (c) 4.3 (d) 4.5
  19. 19.√96 to 1 decimal place? (a) 9.8 (b) 9.5 (c) 9.6 (d) 9.7
  20. 20.Best estimate of 5217 ÷ 67? (a) 750 (b) 75 (c) 7500
  21. 21.Best estimate of 2162 ÷ 23? (a) 10800 (b) 108 (c) 1080
  22. 22.Best estimate of 1247 ÷ 39? (a) 310 (b) 31 (c) 3100
  23. 23.Best estimate of 5472 ÷ 79? (a) 68 (b) 6800 (c) 680
  24. 24.Best estimate of 4954 ÷ 52? (a) 9900 (b) 99 (c) 990
  25. 25.√52 to 1 decimal place? (a) 7.2 (b) 7.0 (c) 7.1 (d) 6.9
  26. 26.Best estimate of 2152 ÷ 29? (a) 72 (b) 720 (c) 7200
  27. 27.Best estimate of 1680 ÷ 79? (a) 21 (b) 210 (c) 2100
  28. 28.Best estimate of 2370 ÷ 48? (a) 470 (b) 4700 (c) 47
  29. 29.Best estimate of 3821 ÷ 87? (a) 4200 (b) 420 (c) 42
  30. 30.Best estimate of 4382 ÷ 48? (a) 8800 (b) 88 (c) 880
  31. 31.Best estimate of 3060 ÷ 33? (a) 102 (b) 1020 (c) 10200
  32. 32.Best estimate of 546 ÷ 26? (a) 180 (b) 18 (c) 1800
  33. 33.Best estimate of 1448 ÷ 66? (a) 21 (b) 2100 (c) 210
  34. 34.Best estimate of 5079 ÷ 88? (a) 5600 (b) 560 (c) 56
  35. 35.Best estimate of 8374 ÷ 88? (a) 9300 (b) 93 (c) 930
  36. 36.Best estimate of 2534 ÷ 32? (a) 8400 (b) 84 (c) 840
  37. 37.Best estimate of 6142 ÷ 88? (a) 68 (b) 680 (c) 6800
  38. 38.Best estimate of 1472 ÷ 82? (a) 18 (b) 1800 (c) 180
  39. 39.Best estimate of 343 ÷ 24? (a) 170 (b) 1700 (c) 17
  40. 40.Best estimate of 5380 ÷ 61? (a) 900 (b) 90 (c) 9000

Answer key

  1. 16
  2. 7.8
  3. 9.7
  4. 44
  5. 5.9
  6. 33
  7. 8.8
  8. 5.8
  9. 7.1
  10. 69
  11. 8.4
  12. 6.2
  13. 21
  14. 7.7
  15. 42
  16. 5.6
  17. 68
  18. 4.5
  19. 9.8
  20. 75
  21. 108
  22. 31
  23. 68
  24. 99
  25. 7.2
  26. 72
  27. 21
  28. 47
  29. 42
  30. 88
  31. 102
  32. 18
  33. 21
  34. 56
  35. 93
  36. 84
  37. 68
  38. 18
  39. 17
  40. 90

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