Standard M\&M's come in six colors: brown, yellow, red, orange, green and blue. If there are 200 M\&M's in a bowl and $20 \%$ are brown, $20 \%$ are yellow, $25 \%$ are red, $15 \%$ are orange, and $10 \%$ are green, how many blue M\&M's are in the bowl?

Step 1 ：The problem provides the percentages of five colors of M&M's: brown, yellow, red, orange, and green. These percentages add up to 90%, so the remaining 10% must be blue.

Step 2 ：We can calculate the number of blue M&M's by applying this percentage to the total number of M&M's in the bowl. The total number of M&M's is 200.

Step 3 ：Using the formula for percentage, which is \( \frac{part}{whole} \times 100\% \), we can find the number of blue M&M's. In this case, the 'part' is the number of blue M&M's, the 'whole' is the total number of M&M's, and the percentage is 10%.

Step 4 ：Rearranging the formula to solve for the 'part', we get \( part = \frac{percentage}{100\%} \times whole \). Substituting the given values, we get \( part = \frac{10\%}{100\%} \times 200 \).

Step 5 ：Solving the equation gives us the number of blue M&M's.

Step 6 ：Final Answer: There are \(\boxed{20}\) blue M&M's in the bowl.