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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 242 · 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 1417 ÷ 63? (a) 2400 (b) 240 (c) 24
  2. 2.√26 to 1 decimal place? (a) 5.0 (b) 5.1 (c) 5.2 (d) 5.3
  3. 3.√61 to 1 decimal place? (a) 8.1 (b) 7.9 (c) 7.8 (d) 8.0
  4. 4.Best estimate of 3402 ÷ 38? (a) 850 (b) 85 (c) 8500
  5. 5.√34 to 1 decimal place? (a) 5.7 (b) 5.8 (c) 5.9 (d) 6.0
  6. 6.Best estimate of 1496 ÷ 72? (a) 21 (b) 2100 (c) 210
  7. 7.Best estimate of 789 ÷ 48? (a) 160 (b) 16 (c) 1600
  8. 8.Best estimate of 1505 ÷ 88? (a) 1700 (b) 17 (c) 170
  9. 9.Best estimate of 3167 ÷ 47? (a) 63 (b) 630 (c) 6300
  10. 10.√43 to 1 decimal place? (a) 6.6 (b) 6.5 (c) 6.4 (d) 6.3
  11. 11.Best estimate of 1684 ÷ 22? (a) 84 (b) 8400 (c) 840
  12. 12.Best estimate of 2987 ÷ 62? (a) 500 (b) 5000 (c) 50
  13. 13.Best estimate of 3320 ÷ 57? (a) 550 (b) 55 (c) 5500
  14. 14.√87 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.4 (d) 9.3
  15. 15.√82 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 9.2 (d) 8.9
  16. 16.Best estimate of 2437 ÷ 41? (a) 61 (b) 6100 (c) 610
  17. 17.√85 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.4 (d) 9.2
  18. 18.√69 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.5 (d) 8.2
  19. 19.Best estimate of 2399 ÷ 53? (a) 48 (b) 480 (c) 4800
  20. 20.√23 to 1 decimal place? (a) 5.1 (b) 4.8 (c) 5.0 (d) 4.9
  21. 21.√27 to 1 decimal place? (a) 5.2 (b) 5.0 (c) 5.3 (d) 5.1
  22. 22.√22 to 1 decimal place? (a) 4.8 (b) 5.0 (c) 4.9 (d) 4.7
  23. 23.√96 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.7 (d) 9.8
  24. 24.√56 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.5 (d) 7.8
  25. 25.√24 to 1 decimal place? (a) 4.8 (b) 5.0 (c) 4.7 (d) 4.9
  26. 26.√98 to 1 decimal place? (a) 9.8 (b) 10.0 (c) 9.9 (d) 10.1
  27. 27.Best estimate of 2399 ÷ 37? (a) 60 (b) 600 (c) 6000
  28. 28.Best estimate of 1057 ÷ 44? (a) 2600 (b) 26 (c) 260
  29. 29.Best estimate of 850 ÷ 37? (a) 210 (b) 21 (c) 2100
  30. 30.√86 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.5 (d) 9.2
  31. 31.Best estimate of 1118 ÷ 83? (a) 1400 (b) 14 (c) 140
  32. 32.Best estimate of 3983 ÷ 47? (a) 80 (b) 800 (c) 8000
  33. 33.Best estimate of 2786 ÷ 41? (a) 7000 (b) 70 (c) 700
  34. 34.Best estimate of 3729 ÷ 44? (a) 930 (b) 93 (c) 9300
  35. 35.√94 to 1 decimal place? (a) 9.7 (b) 9.5 (c) 9.8 (d) 9.6
  36. 36.Best estimate of 2279 ÷ 26? (a) 76 (b) 760 (c) 7600
  37. 37.Best estimate of 3593 ÷ 81? (a) 450 (b) 4500 (c) 45
  38. 38.√28 to 1 decimal place? (a) 5.4 (b) 5.2 (c) 5.3 (d) 5.1
  39. 39.√51 to 1 decimal place? (a) 7.3 (b) 7.0 (c) 7.2 (d) 7.1
  40. 40.√42 to 1 decimal place? (a) 6.6 (b) 6.8 (c) 6.7 (d) 6.5

Answer key

  1. 24
  2. 5.1
  3. 7.8
  4. 85
  5. 5.8
  6. 21
  7. 16
  8. 17
  9. 63
  10. 6.6
  11. 84
  12. 50
  13. 55
  14. 9.3
  15. 9.1
  16. 61
  17. 9.2
  18. 8.3
  19. 48
  20. 4.8
  21. 5.2
  22. 4.7
  23. 9.8
  24. 7.5
  25. 4.9
  26. 9.9
  27. 60
  28. 26
  29. 21
  30. 9.3
  31. 14
  32. 80
  33. 70
  34. 93
  35. 9.7
  36. 76
  37. 45
  38. 5.3
  39. 7.1
  40. 6.5

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