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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 154 · 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 413 ÷ 21? (a) 2100 (b) 210 (c) 21
  2. 2.Best estimate of 2395 ÷ 72? (a) 3400 (b) 340 (c) 34
  3. 3.Best estimate of 1170 ÷ 27? (a) 3900 (b) 39 (c) 390
  4. 4.√70 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.6 (d) 8.5
  5. 5.Best estimate of 4035 ÷ 76? (a) 500 (b) 50 (c) 5000
  6. 6.√37 to 1 decimal place? (a) 6.2 (b) 6.4 (c) 6.3 (d) 6.1
  7. 7.Best estimate of 1432 ÷ 44? (a) 36 (b) 3600 (c) 360
  8. 8.√78 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.8 (d) 8.9
  9. 9.√69 to 1 decimal place? (a) 8.1 (b) 8.4 (c) 8.2 (d) 8.3
  10. 10.Best estimate of 2712 ÷ 89? (a) 300 (b) 30 (c) 3000
  11. 11.Best estimate of 1168 ÷ 69? (a) 170 (b) 1700 (c) 17
  12. 12.Best estimate of 4412 ÷ 52? (a) 880 (b) 8800 (c) 88
  13. 13.Best estimate of 574 ÷ 23? (a) 290 (b) 29 (c) 2900
  14. 14.Best estimate of 2205 ÷ 78? (a) 280 (b) 28 (c) 2800
  15. 15.Best estimate of 3523 ÷ 68? (a) 500 (b) 50 (c) 5000
  16. 16.√53 to 1 decimal place? (a) 7.2 (b) 7.4 (c) 7.3 (d) 7.1
  17. 17.Best estimate of 4744 ÷ 89? (a) 530 (b) 53 (c) 5300
  18. 18.√74 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.6 (d) 8.7
  19. 19.Best estimate of 3006 ÷ 47? (a) 600 (b) 6000 (c) 60
  20. 20.Best estimate of 1531 ÷ 47? (a) 3100 (b) 31 (c) 310
  21. 21.Best estimate of 2486 ÷ 52? (a) 500 (b) 50 (c) 5000
  22. 22.√77 to 1 decimal place? (a) 8.8 (b) 8.6 (c) 8.7 (d) 8.9
  23. 23.√71 to 1 decimal place? (a) 8.5 (b) 8.3 (c) 8.4 (d) 8.6
  24. 24.Best estimate of 314 ÷ 21? (a) 16 (b) 160 (c) 1600
  25. 25.√35 to 1 decimal place? (a) 6.0 (b) 5.7 (c) 5.8 (d) 5.9
  26. 26.√96 to 1 decimal place? (a) 9.8 (b) 9.6 (c) 9.9 (d) 9.7
  27. 27.√42 to 1 decimal place? (a) 6.7 (b) 6.4 (c) 6.5 (d) 6.6
  28. 28.Best estimate of 3844 ÷ 89? (a) 4300 (b) 430 (c) 43
  29. 29.√55 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.6 (d) 7.5
  30. 30.√29 to 1 decimal place? (a) 5.4 (b) 5.6 (c) 5.5 (d) 5.7
  31. 31.Best estimate of 2870 ÷ 32? (a) 96 (b) 9600 (c) 960
  32. 32.Best estimate of 1808 ÷ 49? (a) 3600 (b) 360 (c) 36
  33. 33.Best estimate of 2798 ÷ 89? (a) 3100 (b) 310 (c) 31
  34. 34.Best estimate of 2852 ÷ 36? (a) 71 (b) 710 (c) 7100
  35. 35.Best estimate of 6566 ÷ 79? (a) 820 (b) 8200 (c) 82
  36. 36.Best estimate of 2073 ÷ 59? (a) 35 (b) 350 (c) 3500
  37. 37.Best estimate of 1561 ÷ 51? (a) 310 (b) 3100 (c) 31
  38. 38.Best estimate of 6539 ÷ 81? (a) 8200 (b) 820 (c) 82
  39. 39.Best estimate of 1804 ÷ 32? (a) 60 (b) 6000 (c) 600
  40. 40.Best estimate of 2983 ÷ 32? (a) 9900 (b) 990 (c) 99

Answer key

  1. 21
  2. 34
  3. 39
  4. 8.4
  5. 50
  6. 6.1
  7. 36
  8. 8.8
  9. 8.3
  10. 30
  11. 17
  12. 88
  13. 29
  14. 28
  15. 50
  16. 7.3
  17. 53
  18. 8.6
  19. 60
  20. 31
  21. 50
  22. 8.8
  23. 8.4
  24. 16
  25. 5.9
  26. 9.8
  27. 6.5
  28. 43
  29. 7.4
  30. 5.4
  31. 96
  32. 36
  33. 31
  34. 71
  35. 82
  36. 35
  37. 31
  38. 82
  39. 60
  40. 99

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