### Formula

t1

time at the start

Td

doubling time in consumption of a resource

t2

time at the end

q1

quantity of resource at t1

q2

quantity of resource at t2

t1

time at the start

Td

doubling time in consumption of a resource

t2

time at the end

q1

quantity of resource at t1

q2

quantity of resource at t2

When applied to the constant growth in consumption of a resource, the total amount consumed in one doubling period equals the total amount consumed in all previous periods. Given two measurements of a growing quantity, q1 at time t1 and q2 at time t2, and assuming a constant growth rate, This formula can be used to calculate the start time t1.

Td

t2

q1

q2

t1

Precision

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