US2842871A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Educational device for use in teaching arithmetic
Assignee: Individual
•
Filing: 1956-09-12
•
Granted: 1958-07-15
•
Expires: 1976-09-12
Abstract
No abstract record available.
Inventors
- 👤 John D Laird
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 04:47
CPC Classifications
G; G09; G09B; G09B19/00; G09B19/02
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US564396A
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US958781A
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US1278425A
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US1867888A
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GB407274A
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US2293127A
Cited
US2317107A
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US2458863A
Cited
US2624126A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1961-07-14 | 1962-01-13 | 1962-07-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1965-07-14 | 1966-01-13 | 1966-07-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1969-07-14 | 1970-01-13 | 1970-07-15 | $7700.00 | Window Closed / Lapsed |