🤓 Based on our data, we think this question is relevant for Professor Wynveen's class at UMN.
Remember that when we're performing operations with significant figures, there are two different rules to keep in mind. When we're multiplying (or dividing), we keep the smallest number of sig figs for our answer. Anytime we're adding (or subtracting) significant figures, the rule is that we keep the least decimal places.
If we're adding up numbers in scientific notation that have different exponents, we first need to rewrite them to have the same exponent—otherwise it's harder to tell which number has the least decimal places in relation to the others.
Add ( 9.2 × 103 s ) + ( 8.3 × 104 s ) + ( 0.008 × 106 s ).