which expression represents the largest number?

6.1 times 10^-7
4.1 times 10^-7
3.1 times 10^-8
5.1 times 10^-8

6.1 times 10^-7

To compare the given expressions, we can look at the exponent values.

The largest exponent indicates the largest number. Comparing the exponents:

6.1 times 10^-7 ➠ exponent = -7
4.1 times 10^-7 ➠ exponent = -7
3.1 times 10^-8 ➠ exponent = -8
5.1 times 10^-8 ➠ exponent = -8

Between the options provided, the expression with the largest number is 6.1 times 10^-7.