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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 522 · 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 1249 ÷ 32? (a) 42 (b) 4200 (c) 420
  2. 2.√41 to 1 decimal place? (a) 6.4 (b) 6.2 (c) 6.3 (d) 6.5
  3. 3.Best estimate of 882 ÷ 73? (a) 1300 (b) 13 (c) 130
  4. 4.Best estimate of 946 ÷ 43? (a) 240 (b) 24 (c) 2400
  5. 5.Best estimate of 2011 ÷ 42? (a) 5000 (b) 50 (c) 500
  6. 6.Best estimate of 842 ÷ 24? (a) 42 (b) 4200 (c) 420
  7. 7.√29 to 1 decimal place? (a) 5.3 (b) 5.5 (c) 5.4 (d) 5.2
  8. 8.√34 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.5 (d) 5.8
  9. 9.Best estimate of 3416 ÷ 59? (a) 570 (b) 57 (c) 5700
  10. 10.√92 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.3 (d) 9.4
  11. 11.√21 to 1 decimal place? (a) 4.3 (b) 4.4 (c) 4.6 (d) 4.5
  12. 12.√61 to 1 decimal place? (a) 7.6 (b) 7.8 (c) 7.9 (d) 7.7
  13. 13.√26 to 1 decimal place? (a) 5.0 (b) 5.3 (c) 5.1 (d) 5.2
  14. 14.√69 to 1 decimal place? (a) 8.6 (b) 8.3 (c) 8.4 (d) 8.5
  15. 15.√23 to 1 decimal place? (a) 4.9 (b) 5.1 (c) 4.8 (d) 5.0
  16. 16.Best estimate of 4192 ÷ 68? (a) 60 (b) 600 (c) 6000
  17. 17.Best estimate of 2161 ÷ 76? (a) 2700 (b) 270 (c) 27
  18. 18.Best estimate of 567 ÷ 24? (a) 28 (b) 2800 (c) 280
  19. 19.Best estimate of 1561 ÷ 42? (a) 3900 (b) 390 (c) 39
  20. 20.Best estimate of 6450 ÷ 68? (a) 92 (b) 9200 (c) 920
  21. 21.Best estimate of 3452 ÷ 83? (a) 43 (b) 4300 (c) 430
  22. 22.Best estimate of 664 ÷ 38? (a) 170 (b) 1700 (c) 17
  23. 23.√98 to 1 decimal place? (a) 10.1 (b) 9.8 (c) 10.0 (d) 9.9
  24. 24.Best estimate of 1639 ÷ 42? (a) 41 (b) 410 (c) 4100
  25. 25.√55 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.6 (d) 7.7
  26. 26.Best estimate of 1453 ÷ 56? (a) 2400 (b) 24 (c) 240
  27. 27.√74 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.5 (d) 8.4
  28. 28.Best estimate of 942 ÷ 23? (a) 47 (b) 4700 (c) 470
  29. 29.Best estimate of 2754 ÷ 78? (a) 3400 (b) 340 (c) 34
  30. 30.Best estimate of 1964 ÷ 42? (a) 4900 (b) 49 (c) 490
  31. 31.Best estimate of 2047 ÷ 32? (a) 68 (b) 6800 (c) 680
  32. 32.Best estimate of 2411 ÷ 76? (a) 3000 (b) 300 (c) 30
  33. 33.Best estimate of 655 ÷ 22? (a) 33 (b) 3300 (c) 330
  34. 34.Best estimate of 1157 ÷ 33? (a) 390 (b) 3900 (c) 39
  35. 35.√40 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 6.3 (d) 6.4
  36. 36.Best estimate of 2995 ÷ 69? (a) 430 (b) 4300 (c) 43
  37. 37.Best estimate of 660 ÷ 41? (a) 170 (b) 17 (c) 1700
  38. 38.Best estimate of 988 ÷ 39? (a) 250 (b) 2500 (c) 25
  39. 39.Best estimate of 1732 ÷ 26? (a) 580 (b) 5800 (c) 58
  40. 40.Best estimate of 4576 ÷ 66? (a) 650 (b) 65 (c) 6500

Answer key

  1. 42
  2. 6.4
  3. 13
  4. 24
  5. 50
  6. 42
  7. 5.4
  8. 5.8
  9. 57
  10. 9.6
  11. 4.6
  12. 7.8
  13. 5.1
  14. 8.3
  15. 4.8
  16. 60
  17. 27
  18. 28
  19. 39
  20. 92
  21. 43
  22. 17
  23. 9.9
  24. 41
  25. 7.4
  26. 24
  27. 8.6
  28. 47
  29. 34
  30. 49
  31. 68
  32. 30
  33. 33
  34. 39
  35. 6.3
  36. 43
  37. 17
  38. 25
  39. 58
  40. 65

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