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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 974 · 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 6542 ÷ 72? (a) 93 (b) 930 (c) 9300
  2. 2.√62 to 1 decimal place? (a) 7.8 (b) 7.6 (c) 7.7 (d) 7.9
  3. 3.Best estimate of 2253 ÷ 29? (a) 750 (b) 75 (c) 7500
  4. 4.Best estimate of 944 ÷ 42? (a) 2400 (b) 24 (c) 240
  5. 5.Best estimate of 1831 ÷ 73? (a) 26 (b) 2600 (c) 260
  6. 6.√80 to 1 decimal place? (a) 8.7 (b) 9.0 (c) 8.9 (d) 8.8
  7. 7.Best estimate of 3761 ÷ 56? (a) 630 (b) 63 (c) 6300
  8. 8.√67 to 1 decimal place? (a) 8.2 (b) 8.5 (c) 8.4 (d) 8.3
  9. 9.√45 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.4 (d) 6.7
  10. 10.Best estimate of 2446 ÷ 39? (a) 610 (b) 61 (c) 6100
  11. 11.√90 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.6 (d) 9.4
  12. 12.Best estimate of 3624 ÷ 54? (a) 720 (b) 7200 (c) 72
  13. 13.Best estimate of 4370 ÷ 79? (a) 5500 (b) 55 (c) 550
  14. 14.Best estimate of 4113 ÷ 72? (a) 590 (b) 59 (c) 5900
  15. 15.Best estimate of 677 ÷ 39? (a) 1700 (b) 170 (c) 17
  16. 16.√92 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.9 (d) 9.8
  17. 17.Best estimate of 3081 ÷ 47? (a) 62 (b) 620 (c) 6200
  18. 18.Best estimate of 2465 ÷ 26? (a) 8200 (b) 82 (c) 820
  19. 19.√51 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.4 (d) 7.1
  20. 20.Best estimate of 1592 ÷ 29? (a) 530 (b) 53 (c) 5300
  21. 21.√72 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.4 (d) 8.7
  22. 22.Best estimate of 2337 ÷ 26? (a) 78 (b) 7800 (c) 780
  23. 23.Best estimate of 815 ÷ 49? (a) 16 (b) 1600 (c) 160
  24. 24.Best estimate of 1395 ÷ 86? (a) 16 (b) 160 (c) 1600
  25. 25.Best estimate of 3001 ÷ 72? (a) 4300 (b) 43 (c) 430
  26. 26.Best estimate of 1496 ÷ 42? (a) 370 (b) 37 (c) 3700
  27. 27.√75 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 9.0 (d) 8.7
  28. 28.Best estimate of 755 ÷ 54? (a) 1500 (b) 15 (c) 150
  29. 29.√44 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 6.5 (d) 6.6
  30. 30.√77 to 1 decimal place? (a) 9.1 (b) 8.8 (c) 9.0 (d) 8.9
  31. 31.Best estimate of 1481 ÷ 26? (a) 4900 (b) 490 (c) 49
  32. 32.√86 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.3 (d) 9.2
  33. 33.Best estimate of 4144 ÷ 52? (a) 83 (b) 830 (c) 8300
  34. 34.Best estimate of 457 ÷ 31? (a) 150 (b) 15 (c) 1500
  35. 35.√38 to 1 decimal place? (a) 6.4 (b) 6.5 (c) 6.2 (d) 6.3
  36. 36.Best estimate of 2918 ÷ 67? (a) 4200 (b) 420 (c) 42
  37. 37.Best estimate of 3365 ÷ 54? (a) 670 (b) 6700 (c) 67
  38. 38.Best estimate of 3185 ÷ 81? (a) 4000 (b) 400 (c) 40
  39. 39.Best estimate of 2809 ÷ 34? (a) 94 (b) 940 (c) 9400
  40. 40.√50 to 1 decimal place? (a) 7.2 (b) 7.0 (c) 7.1 (d) 7.3

Answer key

  1. 93
  2. 7.9
  3. 75
  4. 24
  5. 26
  6. 8.9
  7. 63
  8. 8.2
  9. 6.7
  10. 61
  11. 9.5
  12. 72
  13. 55
  14. 59
  15. 17
  16. 9.6
  17. 62
  18. 82
  19. 7.1
  20. 53
  21. 8.5
  22. 78
  23. 16
  24. 16
  25. 43
  26. 37
  27. 8.7
  28. 15
  29. 6.6
  30. 8.8
  31. 49
  32. 9.3
  33. 83
  34. 15
  35. 6.2
  36. 42
  37. 67
  38. 40
  39. 94
  40. 7.1

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