Question 175572
(4X10 ) X (7X10 = 28X10 - 2.8X10 =0.00028 
?
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(4X10) X (7X10)
= 28x10^2 
Divide the 28 by 10 and multiply the 10^2 by 10.
= (2.8/10)x((7x10^2)x10)

= 2.8x10^3
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Cheers,
Stan H.