Although this is the first commemorative US half dollar coin made, so many were released in to circulation, values run from $18.00 to $30.00 depending on the grade. Mint State coins sell around $33.00 to $38.00.
20 half dollars have a face value of a $10.
The 1892-O half dollar is one of the more valuable half dollars. It's worth at least $200 and upwards of almost $800 depending on condition.
The silver melt value of 820 US half dollars is $10,113.74. The silver melt value of 820 1965-70 US half dollars is only $4,135.40.
Please check your coin again and post a new, separate question. There were no "exposition half dollars" minted in 1883. If you're referring to a Columbian Exposition half, these were minted in 1892 and 1893; there's more information at the Related Question.
200
The average value of circulated half dollars is $300.00- $500.00
Kennedy half dollars from banks or in change are just 50 cents.
Half a thousand dollars . . .
1971 Kennedy half dollars are face value only and are still in circulation.
Susan B. Anthony never appeared on the US half dollar coins, only the dollar coins starting in 1979 to 1981 & 1999. The obverse design of your 1902 half dollar is that of "Miss Liberty" and is one of the Barber series (1892-1915) of half dollars. In average circulated condition the coin has a value of $14.00-$30.00
To find out how many half dollars are in $4.50, you can divide the total amount by the value of a half dollar. Since a half dollar is worth $0.50, you divide $4.50 by $0.50. This gives you 9 half dollars, meaning there are 9 half dollars in $4.50.
Be more specific no 1922 half dollars were struck