Which of the following has six significant digits? 0.00005600 km 56.0000 km 0.00056 km 560,000 km?

The "zeroes" before the decimal point are NOT counted as significant digits.

0.00005600 km ...... 4 significant digits
56.0000 km ...... 6 significant digits
0.00056 km ...... 2 significant digits
560,000 km ...... 2 significant digits

...... The answer is : 56.0000 km

Only number containing 6 significant figures is: 56.0000 km

560,000 km

Q.Which of the following has six significant digits? 0.00005600 km 56.0000 km 0.00056 km 560,000 km?
A - 56.0000

2,3&4. the zeros before can be considered significant, unless there are zeros both behind and infront then only the zeros behind are significant:-)