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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 264 · 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 1612 ÷ 81? (a) 20 (b) 2000 (c) 200
  2. 2.Best estimate of 3806 ÷ 47? (a) 7600 (b) 760 (c) 76
  3. 3.Best estimate of 2443 ÷ 81? (a) 310 (b) 3100 (c) 31
  4. 4.√40 to 1 decimal place? (a) 6.0 (b) 6.3 (c) 6.1 (d) 6.2
  5. 5.Best estimate of 1087 ÷ 56? (a) 180 (b) 18 (c) 1800
  6. 6.√69 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.5 (d) 8.4
  7. 7.√44 to 1 decimal place? (a) 6.8 (b) 6.5 (c) 6.7 (d) 6.6
  8. 8.Best estimate of 4524 ÷ 62? (a) 75 (b) 7500 (c) 750
  9. 9.Best estimate of 1352 ÷ 83? (a) 170 (b) 1700 (c) 17
  10. 10.Best estimate of 7197 ÷ 82? (a) 9000 (b) 90 (c) 900
  11. 11.Best estimate of 4138 ÷ 51? (a) 8300 (b) 830 (c) 83
  12. 12.√63 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 8.2 (d) 7.9
  13. 13.√79 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 9.2 (d) 9.1
  14. 14.Best estimate of 3633 ÷ 42? (a) 910 (b) 9100 (c) 91
  15. 15.Best estimate of 7496 ÷ 81? (a) 94 (b) 940 (c) 9400
  16. 16.Best estimate of 1100 ÷ 27? (a) 3700 (b) 37 (c) 370
  17. 17.√78 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 9.0 (d) 9.1
  18. 18.Best estimate of 3969 ÷ 72? (a) 57 (b) 570 (c) 5700
  19. 19.Best estimate of 4354 ÷ 76? (a) 5400 (b) 540 (c) 54
  20. 20.Best estimate of 1412 ÷ 77? (a) 18 (b) 180 (c) 1800
  21. 21.Best estimate of 2058 ÷ 46? (a) 410 (b) 41 (c) 4100
  22. 22.√55 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.4 (d) 7.3
  23. 23.Best estimate of 1753 ÷ 77? (a) 220 (b) 22 (c) 2200
  24. 24.√90 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.5 (d) 9.7
  25. 25.√56 to 1 decimal place? (a) 7.6 (b) 7.5 (c) 7.7 (d) 7.8
  26. 26.√21 to 1 decimal place? (a) 4.7 (b) 4.6 (c) 4.9 (d) 4.8
  27. 27.√96 to 1 decimal place? (a) 9.7 (b) 9.9 (c) 9.8 (d) 10.0
  28. 28.Best estimate of 2914 ÷ 31? (a) 9700 (b) 97 (c) 970
  29. 29.√34 to 1 decimal place? (a) 6.0 (b) 5.8 (c) 5.9 (d) 5.7
  30. 30.√70 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.5 (d) 8.6
  31. 31.√87 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.5 (d) 9.2
  32. 32.Best estimate of 3090 ÷ 52? (a) 620 (b) 62 (c) 6200
  33. 33.√82 to 1 decimal place? (a) 9.2 (b) 9.4 (c) 9.3 (d) 9.1
  34. 34.Best estimate of 2879 ÷ 61? (a) 4800 (b) 480 (c) 48
  35. 35.Best estimate of 2614 ÷ 56? (a) 440 (b) 4400 (c) 44
  36. 36.√41 to 1 decimal place? (a) 6.3 (b) 6.1 (c) 6.2 (d) 6.4
  37. 37.Best estimate of 824 ÷ 52? (a) 16 (b) 160 (c) 1600
  38. 38.Best estimate of 1588 ÷ 23? (a) 7900 (b) 79 (c) 790
  39. 39.Best estimate of 617 ÷ 38? (a) 1500 (b) 150 (c) 15
  40. 40.Best estimate of 4081 ÷ 81? (a) 510 (b) 51 (c) 5100

Answer key

  1. 20
  2. 76
  3. 31
  4. 6.3
  5. 18
  6. 8.3
  7. 6.6
  8. 75
  9. 17
  10. 90
  11. 83
  12. 7.9
  13. 8.9
  14. 91
  15. 94
  16. 37
  17. 8.8
  18. 57
  19. 54
  20. 18
  21. 41
  22. 7.4
  23. 22
  24. 9.5
  25. 7.5
  26. 4.6
  27. 9.8
  28. 97
  29. 5.8
  30. 8.4
  31. 9.3
  32. 62
  33. 9.1
  34. 48
  35. 44
  36. 6.4
  37. 16
  38. 79
  39. 15
  40. 51

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