Question says that you are asked to find 91,321,972 x 0.007004. doing a quick estimate by rounding the numbers in scientific notation.
91,321,972 can be written in scientific notation as [tex] = 9.1 \times 10^7 [/tex] because decimal moved 7 places to the left.
0.007004 can be written in scientific notation as [tex] = 7.0 \times 10^{-3} [/tex] because decimal moved 3 places to the right.
So to get and estimate of their let's multiply
[tex] 9.1 \times 10^7 * 7.0 \times 10^{-3} [/tex]
[tex] = (9.1* 7.0) \times 10^{7-3} [/tex]
[tex] = 63.7 \times 10^{4} [/tex]
= 637000
Hence final answer will be close to 637000.
