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How to Figure Out Significant Figures in a Product

Significant figures are a uniform method of rounding in instances when higher accuracy is required, such as in science. The rules pertain to the accuracy of the number. Any zeros within a number, such as 4.084, are significant since their removal would change the number. The zeros in 4000 aren't significant but the trailing zeros in 4.000 are significant. That's because in the former, the zeros are just place holders, since 4000 could be rewritten 4 x 10^3. But in the latter, the inclusion of the zeros means the number (as a weight, for example) was found to be exactly 4.000.

Instructions

- 1
  Write out the product expression based on the information provided. Use this problem as an example: calculate the length, in inches, of a piece of wire that is 3.432 feet. Set up the multiplication between the measurement and the conversion term of 12 inches/1 foot: 3.432 feet * 12 inches/1 foot.
- 2
  Perform the multiplication: (3.432 feet * 12 inches)/1 foot = (3.432 * 12 inches) = 41.184 inches. Note that the feet/foot cancelled out due to being in the numerator and denominator.
- 3
  Count the number of significant figures in the original terms of the product expression: 3.432 has four significant figures while 12 has two significant figures. Round the final answer to the least accurate, or lowest, number of significant figures provided in the expression: 41.184 becomes 41.

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