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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 165 · 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 1197 ÷ 41? (a) 30 (b) 3000 (c) 300
  2. 2.Best estimate of 2242 ÷ 37? (a) 560 (b) 56 (c) 5600
  3. 3.√31 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.7 (d) 5.8
  4. 4.√30 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.5 (d) 5.4
  5. 5.Best estimate of 710 ÷ 22? (a) 3600 (b) 360 (c) 36
  6. 6.Best estimate of 2894 ÷ 48? (a) 5800 (b) 58 (c) 580
  7. 7.Best estimate of 2340 ÷ 86? (a) 2600 (b) 260 (c) 26
  8. 8.√20 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 4.6 (d) 4.5
  9. 9.√38 to 1 decimal place? (a) 6.1 (b) 5.9 (c) 6.2 (d) 6.0
  10. 10.Best estimate of 1422 ÷ 63? (a) 240 (b) 2400 (c) 24
  11. 11.Best estimate of 2928 ÷ 79? (a) 3700 (b) 37 (c) 370
  12. 12.√90 to 1 decimal place? (a) 9.6 (b) 9.4 (c) 9.7 (d) 9.5
  13. 13.Best estimate of 600 ÷ 32? (a) 20 (b) 200 (c) 2000
  14. 14.Best estimate of 1998 ÷ 56? (a) 330 (b) 3300 (c) 33
  15. 15.Best estimate of 4723 ÷ 88? (a) 52 (b) 5200 (c) 520
  16. 16.Best estimate of 1118 ÷ 34? (a) 370 (b) 37 (c) 3700
  17. 17.√74 to 1 decimal place? (a) 8.6 (b) 8.3 (c) 8.5 (d) 8.4
  18. 18.Best estimate of 1756 ÷ 76? (a) 22 (b) 2200 (c) 220
  19. 19.√45 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 6.9 (d) 7.0
  20. 20.√71 to 1 decimal place? (a) 8.3 (b) 8.1 (c) 8.2 (d) 8.4
  21. 21.Best estimate of 2525 ÷ 41? (a) 630 (b) 63 (c) 6300
  22. 22.Best estimate of 7425 ÷ 79? (a) 930 (b) 93 (c) 9300
  23. 23.√61 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 8.1 (d) 7.8
  24. 24.Best estimate of 1128 ÷ 22? (a) 56 (b) 5600 (c) 560
  25. 25.Best estimate of 2596 ÷ 54? (a) 52 (b) 520 (c) 5200
  26. 26.√23 to 1 decimal place? (a) 4.7 (b) 5.0 (c) 4.8 (d) 4.9
  27. 27.√98 to 1 decimal place? (a) 10.0 (b) 9.8 (c) 9.7 (d) 9.9
  28. 28.√46 to 1 decimal place? (a) 6.7 (b) 6.9 (c) 6.6 (d) 6.8
  29. 29.Best estimate of 6043 ÷ 74? (a) 86 (b) 860 (c) 8600
  30. 30.√35 to 1 decimal place? (a) 6.0 (b) 5.8 (c) 5.9 (d) 6.1
  31. 31.√26 to 1 decimal place? (a) 5.3 (b) 5.1 (c) 5.4 (d) 5.2
  32. 32.√88 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.7 (d) 9.6
  33. 33.Best estimate of 3708 ÷ 39? (a) 9300 (b) 93 (c) 930
  34. 34.Best estimate of 2204 ÷ 78? (a) 2800 (b) 28 (c) 280
  35. 35.Best estimate of 2038 ÷ 27? (a) 68 (b) 680 (c) 6800
  36. 36.√22 to 1 decimal place? (a) 4.5 (b) 4.4 (c) 4.7 (d) 4.6
  37. 37.Best estimate of 470 ÷ 26? (a) 16 (b) 1600 (c) 160
  38. 38.Best estimate of 1061 ÷ 44? (a) 270 (b) 2700 (c) 27
  39. 39.Best estimate of 4927 ÷ 84? (a) 6200 (b) 620 (c) 62
  40. 40.Best estimate of 2239 ÷ 29? (a) 75 (b) 750 (c) 7500

Answer key

  1. 30
  2. 56
  3. 5.6
  4. 5.5
  5. 36
  6. 58
  7. 26
  8. 4.5
  9. 6.2
  10. 24
  11. 37
  12. 9.5
  13. 20
  14. 33
  15. 52
  16. 37
  17. 8.6
  18. 22
  19. 6.7
  20. 8.4
  21. 63
  22. 93
  23. 7.8
  24. 56
  25. 52
  26. 4.8
  27. 9.9
  28. 6.8
  29. 86
  30. 5.9
  31. 5.1
  32. 9.4
  33. 93
  34. 28
  35. 68
  36. 4.7
  37. 16
  38. 27
  39. 62
  40. 75

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