A ballpark figure (an estimate, a guess)

• How many people were at the concert? Give me a ballpark figure

• I think Apple co. makes 100 million dollars a gray. That’s just a ballpark figure, of course.

Out of left filed (unexpected, sudden)

• His comment came out of left field

• He offered me the job out of left field

• He proposed to her out of left field

Hit a home run (to succeed)

• I think I hit a home run on my math test yesterday

• I really hit a home run at my job interview

• That presentation was amazing. You hit a home run!