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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 979 · 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 7351 ÷ 83? (a) 9200 (b) 920 (c) 92
  2. 2.√58 to 1 decimal place? (a) 7.5 (b) 7.4 (c) 7.3 (d) 7.6
  3. 3.Best estimate of 2765 ÷ 64? (a) 460 (b) 46 (c) 4600
  4. 4.Best estimate of 945 ÷ 39? (a) 2400 (b) 24 (c) 240
  5. 5.Best estimate of 2138 ÷ 51? (a) 43 (b) 430 (c) 4300
  6. 6.√98 to 1 decimal place? (a) 10.2 (b) 10.1 (c) 10.0 (d) 9.9
  7. 7.Best estimate of 6066 ÷ 66? (a) 870 (b) 87 (c) 8700
  8. 8.√55 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.3 (d) 7.4
  9. 9.Best estimate of 4556 ÷ 66? (a) 65 (b) 6500 (c) 650
  10. 10.√26 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.1 (d) 5.4
  11. 11.Best estimate of 1973 ÷ 32? (a) 66 (b) 660 (c) 6600
  12. 12.√69 to 1 decimal place? (a) 8.3 (b) 8.5 (c) 8.4 (d) 8.2
  13. 13.√92 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.4 (d) 9.7
  14. 14.Best estimate of 1443 ÷ 76? (a) 1800 (b) 18 (c) 180
  15. 15.√30 to 1 decimal place? (a) 5.7 (b) 5.8 (c) 5.6 (d) 5.5
  16. 16.Best estimate of 3323 ÷ 64? (a) 5500 (b) 55 (c) 550
  17. 17.Best estimate of 457 ÷ 31? (a) 15 (b) 1500 (c) 150
  18. 18.√79 to 1 decimal place? (a) 8.9 (b) 9.2 (c) 9.1 (d) 9.0
  19. 19.√88 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.5 (d) 9.4
  20. 20.√66 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 8.2 (d) 8.3
  21. 21.Best estimate of 745 ÷ 44? (a) 1900 (b) 19 (c) 190
  22. 22.Best estimate of 1167 ÷ 52? (a) 2300 (b) 230 (c) 23
  23. 23.√27 to 1 decimal place? (a) 5.0 (b) 5.2 (c) 5.3 (d) 5.1
  24. 24.Best estimate of 479 ÷ 38? (a) 120 (b) 12 (c) 1200
  25. 25.Best estimate of 2653 ÷ 52? (a) 5300 (b) 530 (c) 53
  26. 26.Best estimate of 1047 ÷ 78? (a) 130 (b) 13 (c) 1300
  27. 27.√24 to 1 decimal place? (a) 4.6 (b) 4.8 (c) 4.7 (d) 4.9
  28. 28.√67 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.5 (d) 8.2
  29. 29.Best estimate of 1417 ÷ 88? (a) 16 (b) 1600 (c) 160
  30. 30.√42 to 1 decimal place? (a) 6.6 (b) 6.8 (c) 6.7 (d) 6.5
  31. 31.Best estimate of 1151 ÷ 71? (a) 16 (b) 1600 (c) 160
  32. 32.Best estimate of 622 ÷ 46? (a) 12 (b) 120 (c) 1200
  33. 33.Best estimate of 1287 ÷ 22? (a) 640 (b) 6400 (c) 64
  34. 34.Best estimate of 6936 ÷ 89? (a) 770 (b) 7700 (c) 77
  35. 35.Best estimate of 4720 ÷ 77? (a) 5900 (b) 59 (c) 590
  36. 36.Best estimate of 835 ÷ 57? (a) 1400 (b) 14 (c) 140
  37. 37.Best estimate of 572 ÷ 46? (a) 1100 (b) 110 (c) 11
  38. 38.Best estimate of 415 ÷ 32? (a) 1400 (b) 140 (c) 14
  39. 39.√89 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.4 (d) 9.7
  40. 40.√63 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 8.0 (d) 7.7

Answer key

  1. 92
  2. 7.6
  3. 46
  4. 24
  5. 43
  6. 9.9
  7. 87
  8. 7.4
  9. 65
  10. 5.1
  11. 66
  12. 8.3
  13. 9.6
  14. 18
  15. 5.5
  16. 55
  17. 15
  18. 8.9
  19. 9.4
  20. 8.1
  21. 19
  22. 23
  23. 5.2
  24. 12
  25. 53
  26. 13
  27. 4.9
  28. 8.2
  29. 16
  30. 6.5
  31. 16
  32. 12
  33. 64
  34. 77
  35. 59
  36. 14
  37. 11
  38. 14
  39. 9.4
  40. 7.9

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