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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 498 · 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 469 ÷ 37? (a) 120 (b) 1200 (c) 12
  2. 2.Best estimate of 1169 ÷ 41? (a) 290 (b) 29 (c) 2900
  3. 3.Best estimate of 717 ÷ 38? (a) 1800 (b) 180 (c) 18
  4. 4.√58 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.5 (d) 7.8
  5. 5.Best estimate of 2157 ÷ 71? (a) 3100 (b) 31 (c) 310
  6. 6.√42 to 1 decimal place? (a) 6.4 (b) 6.5 (c) 6.7 (d) 6.6
  7. 7.Best estimate of 3302 ÷ 67? (a) 4700 (b) 470 (c) 47
  8. 8.√30 to 1 decimal place? (a) 5.3 (b) 5.5 (c) 5.2 (d) 5.4
  9. 9.Best estimate of 1289 ÷ 32? (a) 430 (b) 43 (c) 4300
  10. 10.Best estimate of 4377 ÷ 86? (a) 490 (b) 4900 (c) 49
  11. 11.√94 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 9.7 (d) 9.6
  12. 12.√23 to 1 decimal place? (a) 4.5 (b) 4.6 (c) 4.7 (d) 4.8
  13. 13.√35 to 1 decimal place? (a) 6.0 (b) 5.8 (c) 5.9 (d) 5.7
  14. 14.√48 to 1 decimal place? (a) 7.1 (b) 7.0 (c) 7.2 (d) 6.9
  15. 15.√55 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.4 (d) 7.5
  16. 16.√84 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.3 (d) 9.0
  17. 17.Best estimate of 2090 ÷ 39? (a) 520 (b) 5200 (c) 52
  18. 18.√79 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 9.0 (d) 8.7
  19. 19.Best estimate of 6057 ÷ 66? (a) 870 (b) 87 (c) 8700
  20. 20.Best estimate of 5868 ÷ 72? (a) 84 (b) 8400 (c) 840
  21. 21.Best estimate of 307 ÷ 24? (a) 15 (b) 1500 (c) 150
  22. 22.√82 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.3 (d) 9.0
  23. 23.√88 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.3 (d) 9.4
  24. 24.Best estimate of 3870 ÷ 51? (a) 770 (b) 7700 (c) 77
  25. 25.√69 to 1 decimal place? (a) 8.1 (b) 8.4 (c) 8.2 (d) 8.3
  26. 26.√56 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.3 (d) 7.4
  27. 27.Best estimate of 4304 ÷ 56? (a) 72 (b) 720 (c) 7200
  28. 28.Best estimate of 7396 ÷ 86? (a) 8200 (b) 82 (c) 820
  29. 29.√96 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.8 (d) 9.5
  30. 30.Best estimate of 2667 ÷ 43? (a) 670 (b) 6700 (c) 67
  31. 31.Best estimate of 3085 ÷ 64? (a) 510 (b) 51 (c) 5100
  32. 32.√45 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 7.0 (d) 6.9
  33. 33.Best estimate of 1449 ÷ 34? (a) 48 (b) 480 (c) 4800
  34. 34.Best estimate of 1993 ÷ 47? (a) 4000 (b) 40 (c) 400
  35. 35.Best estimate of 1950 ÷ 48? (a) 3900 (b) 390 (c) 39
  36. 36.√43 to 1 decimal place? (a) 6.7 (b) 6.9 (c) 6.6 (d) 6.8
  37. 37.Best estimate of 3790 ÷ 64? (a) 6300 (b) 630 (c) 63
  38. 38.Best estimate of 553 ÷ 33? (a) 180 (b) 1800 (c) 18
  39. 39.√86 to 1 decimal place? (a) 9.2 (b) 9.5 (c) 9.4 (d) 9.3
  40. 40.Best estimate of 1454 ÷ 42? (a) 36 (b) 360 (c) 3600

Answer key

  1. 12
  2. 29
  3. 18
  4. 7.6
  5. 31
  6. 6.5
  7. 47
  8. 5.5
  9. 43
  10. 49
  11. 9.7
  12. 4.8
  13. 5.9
  14. 6.9
  15. 7.4
  16. 9.2
  17. 52
  18. 8.9
  19. 87
  20. 84
  21. 15
  22. 9.1
  23. 9.4
  24. 77
  25. 8.3
  26. 7.5
  27. 72
  28. 82
  29. 9.8
  30. 67
  31. 51
  32. 6.7
  33. 48
  34. 40
  35. 39
  36. 6.6
  37. 63
  38. 18
  39. 9.3
  40. 36

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