When two floating-point numbers are added, the numbers are first expressed so that they have the same
exponents. For example, if we want to add 1.557+0.04341, the computer would express the numbers as
0.1557×101+0.004341×101. Then the mantissas are added to give 0.160041×101. Now, because this hypothetical
computer only carries a 4-digit mantissa, the excess number of digits get chopped off and the result is 0.1600×101
Notice how the last two digits of the second number (41) that were shifted to the right have essentially been lost
from the computation