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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 550 · 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 732 ÷ 33? (a) 240 (b) 24 (c) 2400
  2. 2.Best estimate of 4309 ÷ 76? (a) 540 (b) 54 (c) 5400
  3. 3.Best estimate of 1922 ÷ 27? (a) 6400 (b) 64 (c) 640
  4. 4.Best estimate of 2393 ÷ 67? (a) 340 (b) 3400 (c) 34
  5. 5.Best estimate of 2259 ÷ 26? (a) 750 (b) 7500 (c) 75
  6. 6.Best estimate of 688 ÷ 38? (a) 1700 (b) 170 (c) 17
  7. 7.√94 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.8 (d) 9.5
  8. 8.Best estimate of 2431 ÷ 34? (a) 8100 (b) 810 (c) 81
  9. 9.Best estimate of 1697 ÷ 31? (a) 57 (b) 5700 (c) 570
  10. 10.Best estimate of 3954 ÷ 47? (a) 790 (b) 7900 (c) 79
  11. 11.√58 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.6 (d) 7.3
  12. 12.√55 to 1 decimal place? (a) 7.4 (b) 7.2 (c) 7.3 (d) 7.1
  13. 13.Best estimate of 533 ÷ 34? (a) 1800 (b) 18 (c) 180
  14. 14.Best estimate of 760 ÷ 39? (a) 19 (b) 190 (c) 1900
  15. 15.Best estimate of 5322 ÷ 59? (a) 890 (b) 8900 (c) 89
  16. 16.√92 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.7 (d) 9.8
  17. 17.Best estimate of 2006 ÷ 56? (a) 3300 (b) 330 (c) 33
  18. 18.Best estimate of 5174 ÷ 57? (a) 86 (b) 8600 (c) 860
  19. 19.Best estimate of 2446 ÷ 78? (a) 3100 (b) 31 (c) 310
  20. 20.Best estimate of 2010 ÷ 41? (a) 500 (b) 50 (c) 5000
  21. 21.Best estimate of 2030 ÷ 26? (a) 6800 (b) 68 (c) 680
  22. 22.√27 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.1 (d) 5.4
  23. 23.√87 to 1 decimal place? (a) 9.4 (b) 9.2 (c) 9.3 (d) 9.1
  24. 24.√35 to 1 decimal place? (a) 5.8 (b) 6.1 (c) 6.0 (d) 5.9
  25. 25.Best estimate of 1993 ÷ 36? (a) 500 (b) 5000 (c) 50
  26. 26.√30 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.8 (d) 5.5
  27. 27.Best estimate of 2741 ÷ 51? (a) 5500 (b) 550 (c) 55
  28. 28.Best estimate of 1970 ÷ 32? (a) 66 (b) 6600 (c) 660
  29. 29.Best estimate of 596 ÷ 29? (a) 200 (b) 2000 (c) 20
  30. 30.√23 to 1 decimal place? (a) 4.9 (b) 4.7 (c) 4.6 (d) 4.8
  31. 31.√21 to 1 decimal place? (a) 4.7 (b) 4.6 (c) 4.9 (d) 4.8
  32. 32.Best estimate of 2343 ÷ 86? (a) 2600 (b) 260 (c) 26
  33. 33.Best estimate of 1534 ÷ 52? (a) 31 (b) 3100 (c) 310
  34. 34.Best estimate of 1390 ÷ 29? (a) 460 (b) 4600 (c) 46
  35. 35.√98 to 1 decimal place? (a) 10.0 (b) 9.9 (c) 10.1 (d) 10.2
  36. 36.Best estimate of 1024 ÷ 57? (a) 170 (b) 1700 (c) 17
  37. 37.√83 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.2 (d) 9.1
  38. 38.Best estimate of 5174 ÷ 84? (a) 6500 (b) 65 (c) 650
  39. 39.Best estimate of 1256 ÷ 27? (a) 4200 (b) 420 (c) 42
  40. 40.√80 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 8.8 (d) 8.9

Answer key

  1. 24
  2. 54
  3. 64
  4. 34
  5. 75
  6. 17
  7. 9.7
  8. 81
  9. 57
  10. 79
  11. 7.6
  12. 7.4
  13. 18
  14. 19
  15. 89
  16. 9.6
  17. 33
  18. 86
  19. 31
  20. 50
  21. 68
  22. 5.2
  23. 9.3
  24. 5.9
  25. 50
  26. 5.5
  27. 55
  28. 66
  29. 20
  30. 4.8
  31. 4.6
  32. 26
  33. 31
  34. 46
  35. 9.9
  36. 17
  37. 9.1
  38. 65
  39. 42
  40. 8.9

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