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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 333 · 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.√87 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.4 (d) 9.1
  2. 2.√89 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.6 (d) 9.3
  3. 3.Best estimate of 3085 ÷ 52? (a) 620 (b) 6200 (c) 62
  4. 4.Best estimate of 7498 ÷ 81? (a) 9400 (b) 94 (c) 940
  5. 5.Best estimate of 1304 ÷ 42? (a) 3300 (b) 330 (c) 33
  6. 6.Best estimate of 1403 ÷ 26? (a) 470 (b) 4700 (c) 47
  7. 7.Best estimate of 2939 ÷ 32? (a) 98 (b) 9800 (c) 980
  8. 8.√92 to 1 decimal place? (a) 9.6 (b) 9.9 (c) 9.8 (d) 9.7
  9. 9.Best estimate of 2300 ÷ 44? (a) 5800 (b) 58 (c) 580
  10. 10.√27 to 1 decimal place? (a) 5.3 (b) 5.4 (c) 5.5 (d) 5.2
  11. 11.Best estimate of 8186 ÷ 86? (a) 9100 (b) 910 (c) 91
  12. 12.Best estimate of 1233 ÷ 79? (a) 150 (b) 1500 (c) 15
  13. 13.√37 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.4 (d) 6.1
  14. 14.Best estimate of 1239 ÷ 62? (a) 2100 (b) 21 (c) 210
  15. 15.Best estimate of 1087 ÷ 62? (a) 1800 (b) 180 (c) 18
  16. 16.√35 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 6.1 (d) 5.8
  17. 17.Best estimate of 885 ÷ 22? (a) 4400 (b) 440 (c) 44
  18. 18.√56 to 1 decimal place? (a) 7.6 (b) 7.5 (c) 7.7 (d) 7.8
  19. 19.√61 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.9 (d) 7.6
  20. 20.Best estimate of 1268 ÷ 66? (a) 18 (b) 180 (c) 1800
  21. 21.√77 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 8.9 (d) 8.7
  22. 22.√58 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.8 (d) 7.5
  23. 23.√51 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.2 (d) 7.1
  24. 24.Best estimate of 2476 ÷ 76? (a) 31 (b) 310 (c) 3100
  25. 25.Best estimate of 440 ÷ 22? (a) 220 (b) 22 (c) 2200
  26. 26.Best estimate of 4050 ÷ 44? (a) 1010 (b) 101 (c) 10100
  27. 27.√31 to 1 decimal place? (a) 5.6 (b) 5.9 (c) 5.7 (d) 5.8
  28. 28.Best estimate of 3146 ÷ 88? (a) 350 (b) 35 (c) 3500
  29. 29.Best estimate of 1448 ÷ 61? (a) 24 (b) 240 (c) 2400
  30. 30.√86 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.3 (d) 9.4
  31. 31.Best estimate of 5788 ÷ 63? (a) 9600 (b) 960 (c) 96
  32. 32.Best estimate of 1061 ÷ 23? (a) 53 (b) 530 (c) 5300
  33. 33.Best estimate of 3079 ÷ 67? (a) 440 (b) 4400 (c) 44
  34. 34.Best estimate of 1886 ÷ 66? (a) 270 (b) 2700 (c) 27
  35. 35.Best estimate of 1768 ÷ 73? (a) 250 (b) 25 (c) 2500
  36. 36.Best estimate of 2123 ÷ 34? (a) 710 (b) 71 (c) 7100
  37. 37.Best estimate of 2429 ÷ 52? (a) 490 (b) 4900 (c) 49
  38. 38.√40 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.4 (d) 6.3
  39. 39.√79 to 1 decimal place? (a) 8.7 (b) 9.0 (c) 8.9 (d) 8.8
  40. 40.Best estimate of 1849 ÷ 24? (a) 9200 (b) 920 (c) 92

Answer key

  1. 9.3
  2. 9.4
  3. 62
  4. 94
  5. 33
  6. 47
  7. 98
  8. 9.6
  9. 58
  10. 5.2
  11. 91
  12. 15
  13. 6.1
  14. 21
  15. 18
  16. 5.9
  17. 44
  18. 7.5
  19. 7.8
  20. 18
  21. 8.8
  22. 7.6
  23. 7.1
  24. 31
  25. 22
  26. 101
  27. 5.6
  28. 35
  29. 24
  30. 9.3
  31. 96
  32. 53
  33. 44
  34. 27
  35. 25
  36. 71
  37. 49
  38. 6.3
  39. 8.9
  40. 92

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