This is the value 40 million
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Explanation:
You could use a calculator, or you could do it mentally. The second approach will have us note that 4*1 = 4, and then we tack on 7 zeros since we have two zeros in 400 and five zeros in 100,000 giving a total of 2+5 = 7
So that means 400*100,000 = 40,000,000 = 40 million
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You could also use scientific notation
400 = 4 x 10^2
100,000 = 1 x 10^5
400*100,000 = (4x10^2)*(1x10^5)
400*100,000 = (4*1) x (10^2*10^5)
400*100,000 = 4 x 10^(2+5)
400*100,000 = 4 x 10^7
400*100,000 = 40,000,000
The exponent of 7 means we move the decimal point 7 spots to the right to go from 4.0 to 40,000,000
