Answer: 3.240576
Explanation:
There are various ways of doing multiplication this is one of them
The wording "keep in mind the rules for significant digits" implies that we are to use these to show where the decimal place goes by approximating the answer. Then conducting the exact calculation.
Consider 0.8 as 8
×
1
10
3
×
8
×
1
10
=
2.4
So the solution is some where a bit above 2.4
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Lets just use the numbers
Multiply both 0.8439 and 3.84 by 1000 to get rid of the decimal place. This makes thing more straight forward. So we end up with:
8439
×
38400
Split up the 38400 into 30000+ 8000 + 400
30000
×
8439
=
253170000
.
8000
×
8439
=
.
67512000
.
.
400
×
8439
=
.
.
3375600
−−−−−−−−−
←
Add
.
324057600
By our approximation we are expecting the form of
2.4
+
small amount
So the answer is
3.240576
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Check by calculator:
0.8439
×
3.84
=
3.240576