Japan · 1664-1739
Takebe Katahiro
Takebe Katahiro was mathematician and mapmaker. He developed high-precision calculations of pi and worked with power-series-like expansions.
Biographical and historical reference works document Takebe Katahiro’s role and the mathematical work summarized on this page.
3-5, 6-8, 9-12, College
The person and the work
Biography
Takebe Katahiro was mathematician and mapmaker associated with Japan. He developed high-precision calculations of pi and worked with power-series-like expansions.
He also participated in surveying and mapmaking projects for the shogunate. Together, these contributions connect fractions, ratios, and percentages, geometry and measurement, and calculus and change to the working problems, tools, and questions of the period.
Mathematical contribution
What this hero added or preserved
Core mathematical work
He developed high-precision calculations of pi and worked with power-series-like expansions.
Method, teaching, or application
He also participated in surveying and mapmaking projects for the shogunate.
Why this matters
The larger lesson
Takebe Katahiro shows that mathematics grows through proof, calculation, observation, design, teaching, or careful records. The lasting lesson is that fractions, ratios, and percentages, geometry and measurement, and calculus and change can turn a difficult question into a method another person can inspect and reuse.
Place the work in time
Timeline
- 1664
Life and working period
Takebe Katahiro worked as mathematician and mapmaker in Japan.
- Legacy
Lasting mathematical connection
He also participated in surveying and mapmaking projects for the shogunate.
Key idea
Proportion preserves a relationship
Takebe Katahiro’s work connects quantities by ratio. Scaling both parts by the same factor keeps the relationship unchanged.
The ratio 6:9 scaled by 6 becomes 36:54.
Try it yourself
Scale a ratio
Scale the ratio 6:9 by a factor of 6.
- Multiply the first term by the scale factor.
- Multiply the second term by the same factor.
- Confirm that both ratios simplify to the same value.
Show the answer
The scaled ratio is 36:54.
Math at work
Navigators and pilots use the same habits
Navigators and pilots use fractions, ratios, and percentages to plan, compare, test, or communicate decisions. Takebe Katahiro’s work provides a historical example of that connection.
Keep curiosity alive
A little-known fact
He also participated in surveying and mapmaking projects for the shogunate.
Takebe Katahiro matters because of only one famous formula or anecdote.
The documented record is broader: He developed high-precision calculations of pi and worked with power-series-like expansions.
Keep exploring
Connected learning paths
Related math terms
- Ratio
- Proportion
- Percentage
- Angle
Practice these ideas
- Fractions & DecimalsWork with fractions, decimals, percentages, and conversions.
- Pre-AlgebraBridge arithmetic and algebra with integers, ratios, and equations.
- GeometryExplore shapes, angles, area, perimeter, volume, and classification.
- Advanced GeometryPractice coordinate geometry, transformations, vectors, and solids.
- Basic CalculusPractice introductory limits, derivatives, and integrals.