Use estimation to check answers to calculations and determine, in the context of a problem, an appropriate degree of accuracy
| 1. | About Half: 780 390 96 1080 | |
| 2. | About Half: 63 585 789 6232 | |
| 3. | About Half: 62 585 4112 38 120 6258 | |
| 4. | About Half: 89 590 926 17 680 1834 | |
| 5. | About Half: 67 899 77 020 7020 8199 | |
| 6. | About Half: 59 730 53 030 5020 5902 | |
| 7. | About Half: 42 289 48 928 409 4120 | |
| 8. | About Half: 34 008 21 119 1987 3369 | |
| 9. | About Half: 4200.07. 350.9, 80.2, 6004.5 | |
| 10. | About Half: 8002.6, 30 204.6, 206 100.5, 5100.9 | |
| 11. | About Half: 616.2, 12 101.3, 24 336.9, 48 244.6 | |
| 12. | About Half: 20 265.7, 22 369.5, 24 287.6, 28 369.7 | |
| 13. | About Half: 120 369 10 493 258.69 1021.36 | |
| 14. | About Half: 5 125 321 10 205.68 8 200 458 60 501.36 | |
| 15. | About Half: 6 250 369 50 125.59 1 002 369 100 125.99 | |
| 16. | About Half: 12 608.9 15 093.89 4102.4 20 201.369 | |
| 17. | About Half: 2 200 420 500 287.36 220 420.36 50 287.36 | |
| 18. | About Half: 5 750 500 5 112 098 771 597 1 190 785 | |
| 19. | About Half: 3 890 476 77 890.98 812 496.87 3 098 847 | |
| 20. | About Half: 487 990 990 871109 893 412 345.92 | |
| 21. | About Half: 2 258 147 1258.36 202 250 820 258 | |
| 22. | About Half: 2 268 601 18 369 281 258 1833.33 | |
| 23. | About Half: 209.42 29.42 94.24 290.81 | |
| 24. | About Half: 601.8 900.7 505.6 208.5 | |
| 25. | About to divide 2423/40 | |
| 26. | About to divide 3198/80 | |
| 27. | About to divide 8068/90 | |
| 28. | About to divide: Click the best estimate of the answer | |
| 29. | About to divide 4856/80 | |
| 30. | Degrees of heat: How many times hotter is the Earth's inner core than the upper mantle? | |
| 31. | Rolling rivers: Compare the length of the Nile with the length of the Murrumbidgee | |
| 32. | About Half: 2009 6992 | |
| 33. | About Half: 6978 4012 | |
| 34. | About Half: 8019 998 | |
| 35. | About Half: 4975 3006 | |
| 36. | About Half: 1997 6011 | |
| 37. | About Half: 7007.9 2986.2 | |
| 38. | About Half: 7991.6 5015.8 | |
| 39. | About Half: 2010.7 8979.5 | |
| 40. | About Half: 3999.1 9027.4 | |
| 41. | About Half: 1003.3 5985.7 | |
| 42. | About Half: 1979.6 6005.1 | |
| 43. | About Half: 4015.9 1998.1 | |
| 44. | About Half: 3002.5 8978.5 | |
| 45. | About Half: 19 837.91, 70 011.09 | |
| 46. | About Half: 30 198.11, 89 997.23 | |
| 47. | About Half: 59 763.25, 40 289.37 |