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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 912 · 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.√74 to 1 decimal place? (a) 8.4 (b) 8.7 (c) 8.5 (d) 8.6
  2. 2.√22 to 1 decimal place? (a) 4.6 (b) 4.8 (c) 4.9 (d) 4.7
  3. 3.Best estimate of 2599 ÷ 86? (a) 290 (b) 29 (c) 2900
  4. 4.Best estimate of 853 ÷ 22? (a) 4300 (b) 43 (c) 430
  5. 5.√96 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.5 (d) 9.6
  6. 6.Best estimate of 3573 ÷ 71? (a) 510 (b) 51 (c) 5100
  7. 7.Best estimate of 2470 ÷ 27? (a) 82 (b) 8200 (c) 820
  8. 8.Best estimate of 2467 ÷ 87? (a) 270 (b) 2700 (c) 27
  9. 9.√24 to 1 decimal place? (a) 4.8 (b) 5.1 (c) 5.0 (d) 4.9
  10. 10.√23 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 4.5 (d) 4.6
  11. 11.√27 to 1 decimal place? (a) 5.1 (b) 5.3 (c) 5.2 (d) 5.0
  12. 12.√41 to 1 decimal place? (a) 6.2 (b) 6.5 (c) 6.3 (d) 6.4
  13. 13.Best estimate of 1851 ÷ 37? (a) 4600 (b) 46 (c) 460
  14. 14.√58 to 1 decimal place? (a) 7.7 (b) 7.5 (c) 7.8 (d) 7.6
  15. 15.Best estimate of 5296 ÷ 64? (a) 8800 (b) 880 (c) 88
  16. 16.Best estimate of 3818 ÷ 66? (a) 55 (b) 550 (c) 5500
  17. 17.√78 to 1 decimal place? (a) 8.6 (b) 8.8 (c) 8.5 (d) 8.7
  18. 18.Best estimate of 1260 ÷ 37? (a) 320 (b) 32 (c) 3200
  19. 19.Best estimate of 3494 ÷ 67? (a) 500 (b) 5000 (c) 50
  20. 20.√59 to 1 decimal place? (a) 7.4 (b) 7.7 (c) 7.6 (d) 7.5
  21. 21.Best estimate of 2724 ÷ 47? (a) 5400 (b) 540 (c) 54
  22. 22.Best estimate of 2171 ÷ 36? (a) 540 (b) 54 (c) 5400
  23. 23.√51 to 1 decimal place? (a) 7.1 (b) 6.9 (c) 7.0 (d) 7.2
  24. 24.Best estimate of 633 ÷ 27? (a) 2100 (b) 210 (c) 21
  25. 25.Best estimate of 3156 ÷ 49? (a) 630 (b) 6300 (c) 63
  26. 26.√26 to 1 decimal place? (a) 5.2 (b) 5.0 (c) 5.3 (d) 5.1
  27. 27.Best estimate of 717 ÷ 24? (a) 3600 (b) 360 (c) 36
  28. 28.√69 to 1 decimal place? (a) 8.3 (b) 8.1 (c) 8.2 (d) 8.4
  29. 29.√84 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.0 (d) 9.1
  30. 30.Best estimate of 644 ÷ 33? (a) 2100 (b) 21 (c) 210
  31. 31.Best estimate of 1649 ÷ 32? (a) 55 (b) 550 (c) 5500
  32. 32.Best estimate of 3304 ÷ 52? (a) 660 (b) 6600 (c) 66
  33. 33.√29 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.6 (d) 5.5
  34. 34.Best estimate of 4478 ÷ 66? (a) 64 (b) 6400 (c) 640
  35. 35.√40 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.5 (d) 6.2
  36. 36.√77 to 1 decimal place? (a) 8.9 (b) 9.1 (c) 8.8 (d) 9.0
  37. 37.√30 to 1 decimal place? (a) 5.4 (b) 5.5 (c) 5.6 (d) 5.7
  38. 38.Best estimate of 2489 ÷ 52? (a) 5000 (b) 500 (c) 50
  39. 39.Best estimate of 765 ÷ 26? (a) 2600 (b) 260 (c) 26
  40. 40.√46 to 1 decimal place? (a) 7.1 (b) 7.0 (c) 6.9 (d) 6.8

Answer key

  1. 8.6
  2. 4.7
  3. 29
  4. 43
  5. 9.8
  6. 51
  7. 82
  8. 27
  9. 4.9
  10. 4.8
  11. 5.2
  12. 6.4
  13. 46
  14. 7.6
  15. 88
  16. 55
  17. 8.8
  18. 32
  19. 50
  20. 7.7
  21. 54
  22. 54
  23. 7.1
  24. 21
  25. 63
  26. 5.1
  27. 36
  28. 8.3
  29. 9.2
  30. 21
  31. 55
  32. 66
  33. 5.4
  34. 64
  35. 6.3
  36. 8.8
  37. 5.5
  38. 50
  39. 26
  40. 6.8

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