Patent US2899756A successfully refreshed from Google Patents.
US2899756A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Arithmetic tutoring device
Assignee: —
•
Filing: —
•
Granted: 1959-08-18
•
Expires: 1976-08-18
Abstract
No abstract record available.
Inventors
No inventors recorded.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 09:16
CPC Classifications
G; G09; G09B; G09B19/00; G09B19/02
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
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US1696988A
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US2050498A
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US2055159A
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US2516410A
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US2472439A
Cited
US2645038A
Cited
US2769640A
Cited
GB744637A
Cited
US2782530A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1962-08-17 | 1963-02-16 | 1963-08-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1966-08-17 | 1967-02-16 | 1967-08-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1970-08-17 | 1971-02-16 | 1971-08-18 | $7700.00 | Window Closed / Lapsed |