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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 749 · 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.√61 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 7.7 (d) 7.6
  2. 2.√26 to 1 decimal place? (a) 5.1 (b) 5.2 (c) 5.3 (d) 5.4
  3. 3.√80 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 9.2 (d) 8.9
  4. 4.Best estimate of 5042 ÷ 72? (a) 7200 (b) 720 (c) 72
  5. 5.Best estimate of 1132 ÷ 58? (a) 190 (b) 19 (c) 1900
  6. 6.Best estimate of 5593 ÷ 87? (a) 6200 (b) 62 (c) 620
  7. 7.√92 to 1 decimal place? (a) 9.8 (b) 9.6 (c) 9.5 (d) 9.7
  8. 8.Best estimate of 4649 ÷ 89? (a) 52 (b) 5200 (c) 520
  9. 9.Best estimate of 1078 ÷ 58? (a) 180 (b) 18 (c) 1800
  10. 10.√48 to 1 decimal place? (a) 6.8 (b) 6.7 (c) 6.6 (d) 6.9
  11. 11.Best estimate of 1475 ÷ 79? (a) 180 (b) 1800 (c) 18
  12. 12.√90 to 1 decimal place? (a) 9.6 (b) 9.4 (c) 9.7 (d) 9.5
  13. 13.Best estimate of 1459 ÷ 46? (a) 29 (b) 290 (c) 2900
  14. 14.√29 to 1 decimal place? (a) 5.2 (b) 5.4 (c) 5.1 (d) 5.3
  15. 15.√66 to 1 decimal place? (a) 8.4 (b) 8.2 (c) 8.1 (d) 8.3
  16. 16.Best estimate of 2112 ÷ 43? (a) 5300 (b) 530 (c) 53
  17. 17.Best estimate of 1730 ÷ 33? (a) 5800 (b) 580 (c) 58
  18. 18.Best estimate of 962 ÷ 26? (a) 3200 (b) 320 (c) 32
  19. 19.Best estimate of 1222 ÷ 49? (a) 2400 (b) 240 (c) 24
  20. 20.√37 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 5.8 (d) 6.1
  21. 21.Best estimate of 344 ÷ 26? (a) 1100 (b) 11 (c) 110
  22. 22.Best estimate of 987 ÷ 63? (a) 160 (b) 16 (c) 1600
  23. 23.Best estimate of 2895 ÷ 34? (a) 9700 (b) 97 (c) 970
  24. 24.√42 to 1 decimal place? (a) 6.4 (b) 6.5 (c) 6.6 (d) 6.7
  25. 25.√74 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.7 (d) 8.6
  26. 26.Best estimate of 1144 ÷ 26? (a) 3800 (b) 38 (c) 380
  27. 27.Best estimate of 2606 ÷ 47? (a) 5200 (b) 52 (c) 520
  28. 28.√51 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 7.1 (d) 7.0
  29. 29.Best estimate of 4501 ÷ 74? (a) 64 (b) 640 (c) 6400
  30. 30.√55 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.7 (d) 7.4
  31. 31.√34 to 1 decimal place? (a) 5.9 (b) 5.7 (c) 5.8 (d) 5.6
  32. 32.Best estimate of 2388 ÷ 42? (a) 60 (b) 6000 (c) 600
  33. 33.Best estimate of 2838 ÷ 63? (a) 4700 (b) 47 (c) 470
  34. 34.√83 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 8.9 (d) 9.1
  35. 35.Best estimate of 1400 ÷ 46? (a) 2800 (b) 280 (c) 28
  36. 36.Best estimate of 2180 ÷ 33? (a) 73 (b) 730 (c) 7300
  37. 37.Best estimate of 1431 ÷ 64? (a) 2400 (b) 24 (c) 240
  38. 38.Best estimate of 677 ÷ 32? (a) 2300 (b) 230 (c) 23
  39. 39.Best estimate of 2659 ÷ 78? (a) 330 (b) 33 (c) 3300
  40. 40.Best estimate of 655 ÷ 22? (a) 33 (b) 330 (c) 3300

Answer key

  1. 7.8
  2. 5.1
  3. 8.9
  4. 72
  5. 19
  6. 62
  7. 9.6
  8. 52
  9. 18
  10. 6.9
  11. 18
  12. 9.5
  13. 29
  14. 5.4
  15. 8.1
  16. 53
  17. 58
  18. 32
  19. 24
  20. 6.1
  21. 11
  22. 16
  23. 97
  24. 6.5
  25. 8.6
  26. 38
  27. 52
  28. 7.1
  29. 64
  30. 7.4
  31. 5.8
  32. 60
  33. 47
  34. 9.1
  35. 28
  36. 73
  37. 24
  38. 23
  39. 33
  40. 33

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