One question: doesn't the definition of a Yojana vary a lot, with differences across texts and times? I am also very curious about Ancient Indian math, but I think we should also question how results were calculated.
For instance, 108 is a sacred number in Hindu and Buddhist cultures. Some people say it was chosen because the ratio of distances of the Sun and the Moon to Earth is 108 times their respective diameters, and Ancient Indians knew that! But how did they know that?
Make a wooden disc and a stick whose length is 108 times the diameter of the disc. Attach the disc to one end of the stick and hold the other end near your eye. Observe that the disc has the same apparent diameter as the moon, eclipsing it. You could do the same with the sun through light clouds or mist, but be careful, obviously. There are indications that some ancient peoples, such as the builders of Stonehenge, were sufficiently interested in astronomical observation that they might have done a measurement like that and noted the result.
For instance, 108 is a sacred number in Hindu and Buddhist cultures. Some people say it was chosen because the ratio of distances of the Sun and the Moon to Earth is 108 times their respective diameters, and Ancient Indians knew that! But how did they know that?