please check:

Decide what number or description is indicated by the capitalzied words by using your knowledge about prefixes.

1. Our group sat in a SEMICIRCLE.
half circle

2. An OCTOPUS has _____ arms.
eight

3. Our city celebrated its SESQUICENTENNIAL.
150 years

4. A DECATHLON has _____ separate events.
ten

5. OCTOGENARIANS are people who are in their _____.
eighties

6. How often is a BIANNUAL magazine published?
twise

7. The J.F. Max Company celebrated its CENTENNIAL.
100 year anniversary

8. The acting DUET consisted of _____ acters.
two

9. He positioned his camera on a TRIPOD before the play started.
three

10. A year LESS than a DECADE is _____ years.
nine

thanks

Right.

Great job on your explanations! Here's a breakdown of the answers you provided:

1. The word "semicircle" has the prefix "semi-" which means "half." Therefore, a semicircle is a half circle.

2. The prefix "octo-" means "eight." An octopus has eight arms.

3. The term "sesquicentennial" has the prefix "sesqui-" which means "one and a half." Therefore, a sesquicentennial refers to 150 years.

4. The prefix "deca-" means "ten." A decathlon consists of ten separate events.

5. The prefix "octo-" means "eight." Octogenarians are people who are in their eighties.

6. The prefix "bi-" means "two." A biannual magazine is published twice a year.

7. The term "centennial" has the prefix "centi-" which means "one hundred." Therefore, a centennial refers to a 100-year anniversary.

8. The prefix "du-" means "two." A duet consists of two actors.

9. The prefix "tri-" means "three." A tripod has three legs that support the camera.

10. The prefix "de-" means "ten." A decade refers to a period of ten years. Therefore, a year less than a decade would be nine years.

Great job again! Let me know if there's anything else I can help you with.