Patent US2722754A successfully refreshed from Google Patents.
US2722754A
Expired / Lapsed
US
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Device for teaching elementary mathematics
Assignee: Individual
•
Filing: 1951-11-08
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Granted: 1955-11-08
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Expires: 1971-11-08
Abstract
No abstract record available.
Inventors
- 👤 Herbert L Slote
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 23:28
CPC Classifications
G; G09; G09B; G09B19/00; G09B19/02
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US151971A
Cited
US798337A
Cited
US1168949A
Cited
US1531070A
Cited
GB320046A
Cited
GB428287A
Cited
US2254498A
Cited
US2570625A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1958-11-07 | 1959-05-09 | 1959-11-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1962-11-07 | 1963-05-09 | 1963-11-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1966-11-07 | 1967-05-09 | 1967-11-08 | $7700.00 | Window Closed / Lapsed |