The speed of light is about 1.86×10⁵ miles/second. 10⁵ is 100000 so the speed is 186,000 miles/sec. Actually, it is about 186,252 miles/sec, but if we can only store 3 digits of mantissa, we would have to approximate it with 186,000. If we wanted to represent the number 1860, we could use 1.86×10³, and our level of accuracy (the number of digits in the mantissa) would be identical to that of our speed of light value. Obviously 10⁵ is much larger than 10³, 100 times larger in fact, so the speed of light is much larger than 1860 yet both numbers have 1.86 as their mantissa.